OpenAI's rollout of GPT-5 has faced criticism from users attached to older models, who say the new version lacks the character of its predecessors.

GPT-5 was designed as an all-in-one model, featuring a lightweight version for rapid responses and a reasoning version for complex tasks. A routing system determines which option to use, although users can manually select from several alternatives.

Modes include Auto, Fast, Thinking, Thinking mini, and Pro, with the last available to Pro subscribers for$200 monthly. Standard paid users can still access GPT-4o, GPT-4.1, 4o-mini, and even 3o through additional settings.

Chief executive Sam Altman has said the long-term goal is to give users more control over ChatGPT's personality, making customisation a solution to concerns about style. He promised ample notice before permanently retiring older models.