What are the new features of GPT-5?
OpenAI describes GPT-5 as “the smartest and most useful model yet—with built-in reasoning that makes expert knowledge accessible to everyone” (OpenAI, 2025). According to the official GPT-5 system card, OpenAI describes GPT-5 as “a unified system with a fast model, a deeper reasoning model (GPT-5 Thinking), and a real-time router that quickly decides which model to use based on the type of conversation and complexity.” The “router” is an administrative layer or decision-making logic, not necessarily a standalone “hardware router” in the traditional sense. The model to be used is decided on a per-prompt basis. The model promises shorter response times and more stable performance, while also offering longer dialogue times and personalized responses.
This makes GPT-5 more versatile for use in a wide variety of areas, from content creation and programming to business analysis. The following graphic demonstrates the system architecture and underlying models for GPT-5:
While companies and developers welcome this potential, critics are increasingly voicing concerns about data protection and social implications.
Here is an overview of the key new features, based on OpenAI’s release blog:
- Since April 2026, GPT-5.5 has been OpenAI’s flagship model, with variants such as Instant, Thinking and Pro catering to different performance levels.
- ChatGPT relies on a routing system rather than model versions: depending on the task, it automatically chooses between speed and deep reasoning.
- GPT-5.4, as a transitional and efficiency layer, remains relevant, particularly via mini and nano models for light or scalable tasks.
- Older models such as GPT-4o, GPT-4.1 and GPT-5.1 have largely been removed from ChatGPT and replaced by the new GPT-5.x generation.
- Updates are increasingly communicated via product capabilities and system behaviour, rather than via traditional model names.
Versions and Usage of the GPT Models
Here an overview of the current models of OpenAI's GPT used:
Versions and use of the GPT models
GPT-5 represents the ongoing evolution of OpenAI’s AI models. GPT-4 laid the groundwork with advanced text and image processing and reliable accuracy in everyday tasks. GPT-4o, as a turbo-optimised variant, operated faster and more accurately, and also experimented with audio and video processing as well as empathetic and emotional tone. As the new generation, GPT-5 combines the highest accuracy with native multimodality for text, image, audio and video, an extremely large context window, and an integrated thinking mode. The choice of model depends on the required accuracy and capacity, depending on the use case.
The latest flagship model is GPT-5.5; GPT-5.4 continues to be used as an efficiency model. GPT-4o and several GPT-4 and GPT-5.1 models were removed from ChatGPT in February 2026. Within ChatGPT, GPT-5.5 (Instant, Thinking, Pro) and, in some cases, GPT-5.4 and GPT-5.3 models are available as part of a routing system. OpenAI is clearly focusing on the GPT-5.x generation and a more system-based model architecture.
Also new: ChatGPT Go launches a new, affordable subscription tier between Free and Plus, significantly broadening access – strategically well-timed just ahead of the planned advertising rollouts. In parallel, OpenAI is officially confirming for the first time the introduction of advertising in ChatGPT, particularly via ‘Sponsored Recommendations’ for Free and Go users.
GPT-5 vs. GPT-4/4o
Whilst GPT-4 already represented a major leap forward in AI-powered text and image processing, GPT-5 is now setting new standards in precisely this area of accuracy and performance. GPT-4 offers developers and businesses a powerful platform for applications in text processing, chatbots, content generation and much more. GPT-5 significantly expands these capabilities: whilst GPT-4 Turbo and GPT-4o in particular already supported multimodality, GPT-5 allows for audio and video content in addition to text and images, offers a significantly larger context window and has introduced the new thinking mode. Furthermore, the standard GPT-5 model has significantly improved programming capabilities compared to GPT-4o.
An overview of GPT-5 models
(As of June 2026)
The GPT-5 model series is a tiered system comprising flagship, reasoning and efficiency models, which differ in terms of computational cost, depth of reasoning, response quality and primary use case. The routing system dynamically selects the most appropriate model.
GPT-5.5 (aktuelle Flagship-Generation, ab April/Mai 2026)
GPT-5.5 wurde am 23. April 2026 veröffentlicht und wird von OpenAI als das bislang intelligenteste und intuitivste Modell beschrieben. GPT-5.5 ist in drei Varianten verfügbar, Thinking (für Plus-Nutzer und höher in ChatGPT), Pro (für Pro-, Business- und Enterprise-Nutzer) sowie Instant, seit 5. Mai 2026 das neue Standard-Alltagsmodell für alle ChatGPT-Nutzer. Das Modell reduziert halluzinierte Antworten in sensiblen Bereichen stark und kann zudem auf vergangene Gespräche, Dateien und Gmail zugreifen.
GPT-5.4 (Frontier and Efficiency models)
The Frontier model combines advances in reasoning, coding and agent-based workflows, marking a structural evolution of the entire product line. It is the first mainstream model to directly integrate the Frontier coding capabilities of GPT-5.3 Codex and features an extremely large context window. Version 5.4 is available in the Thinking, Pro, mini and nano variants.
GPT-5.3 / GPT-5.3 Codex (special model)
GPT-5.3 Instant was the fast and powerful model for everyday tasks in ChatGPT until May 2026, but has since been replaced by GPT-5.5 Instant. The focus was on stability and reducing hallucinations, as well as delivering more consistent responses to multi-step reasoning tasks.
Codex variants: GPT-5.3-Codex was released in February 2026 and specialises in code generation, speed, repository search and terminal execution.
GPT-5.2 (discontinued)
The GPT-5.2 model (December 2025) brought significant improvements in structured reasoning and professional knowledge work; however, it is scheduled to be phased out of ChatGPT on 5 June 2026 and has largely been integrated into GPT-5.3/5.4.
GPT-5.1 (discontinued)
5.1 was a temporary model featuring improved personality settings and instruction handling; it was removed from ChatGPT in March 2026. Existing conversations were automatically redirected to the respective successor models.+
GPT-5 (the foundation of the generation; no longer active in the frontend)
The first version of Generation 5 introduced adaptive model selection between fast and deep responses. GPT-5 (first-generation Instant/Thinking) was removed from ChatGPT in February 2026, though parts of the architecture remain in the routing system as a conceptual basis.
Current debates surrounding GPT-5: Why is the new model so divisive?
The issues of security and transparency are particularly divisive, as are trust and sustainability in the context of GPT models. The disappointed reactions to the GPT-5 models appear to stem from overly high expectations and hype, which are being better managed by OpenAI’s competitors.
High expectations and criticism of mistakes
Users on platforms such as X and Reddit reported poorer performance compared to GPT-4o. Expectations of the new models proved to be too high, and the question “What has happened to GPT?” is frequently being asked. Some users criticised the new model as cold and distant, particularly in comparison to GPT-4o, which was especially known for its emotionally rich conversations. This reignited the debate about user engagement and the emotional aspects of AI models. Furthermore, Sam Altman, the CEO of OpenAI, admitted to blunders during the rollout of GPT-5: the bar charts showing model performance displayed in the launch livestream contained errors, which Altman attributed to human error caused by exhaustion. (Reddit, 2025)
Advertising and user trust in 2026
As recently as 2024, Altman described advertising as a “last resort” for ChatGPT; however, an official advertising trial has been running in ChatGPT in the US since 9 February 2026 and has been gradually expanded since then. Adverts are always clearly labelled as “Sponsored” and visually separated below the actual ChatGPT response. The so-called “Sponsored Recommendations” are displayed in line with the ongoing conversation. Advertising is not yet active in Germany and the DACH region, although the ChatGPT Go subscription page in German already displays the note “This plan may contain advertising”. Although the move sparked significant online criticism regarding user trust and data protection, OpenAI has so far reported no negative impact on trust metrics. (OpenAI, 2026)
Another point of criticism concerns the source and reliability of the data used by the models. Versions such as GPT-5.2 have repeatedly been found to cite an AI-generated online encyclopaedia that lacks human editorial oversight. The risks of hallucinations and misinformation have not been completely eliminated, and OpenAI must address this challenge strategically and make continuous improvements.
Rapid model development and fierce competition
The rapid succession of releases, from GPT-5.1 and 5.2 to 5.3 and 5.4, within just a few months is causing increasing confusion among users and developers. The discussions that have emerged have centred primarily on the following questions:
- Will AI models become more personalised in the future?
- Are smaller, specialised variants more useful?
- Are new generations of models being released and replaced too soon?
- What about the quality and ethics of the new models?
OpenAI’s market leadership is under pressure: a lack of transparency, distortion of competition and changes such as the introduction of advertising are leading users to increasingly turn to alternatives on the market, such as Google Gemini or Anthropic’s Claude. Anthropic is deliberately positioning its chatbot, Claude, as an ad-free alternative.
Assessment and Outlook
Despite impressive technical advances, the GPT-5 cycle shows that OpenAI is increasingly facing growing competitive pressure from major rivals such as Google and declining trust among its own user base. Nevertheless, GPT-5 has now established itself as an integral part of numerous enterprise and developer platforms, including Microsoft Copilot and Azure AI Foundry. This widespread integration optimises the use of GPT-5 in business processes and customer service applications. The introduction of a hybrid multi-model system enables more efficient task distribution and leads to improved performance when handling complex queries. Benchmark tests confirm higher accuracy and reduced error rates compared to previous models.
"GPT-5's strengths lie primarily in agentic applications, especially in the area of in-depth research and as an assistant in programming."
Patrick from moinAI, CEO & Head of Research
What about gpt-oss?
With less buzz in the general news world, we at moinAI are very excited about the open source model gpt-oss. This was introduced in the same week as the GPT-5 models. The advantage of the oss variant for moinAI as a SaaS provider is that it is very fast and performs similarly to the popular GPT-4o model. This makes it possible to offer the service at its current excellent level, hosted entirely on German servers at moinAI, without dependence on providers such as OpenAI or Azure. This ensures that customer data is never passed on to third parties.
What can we expect from future models?
Future models such as GPT-6 could therefore have better personalisation features to respond to individual user preferences, as well as further increasing the context window and offering even more accurate multimodality. However, exact values are not yet available, and the official announcement of GPT-6 and its specific features remains to be seen.
GPT-5.5 and other models mark a significant advance in AI development, but there are complaints about lower transparency and control compared to previous models, and responses are perceived as too formal and less appealing. OpenAI needs to address this feedback and incorporate it into future releases.
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