Interesting that they're releasing separate gpt-5.1-instant and gpt-5.1-thinking models. The previous gpt-5 release made of point of simplifying things by letting the model choose if it was going to use thinking tokens or not. Seems like they reversed course on that?
I was prepared to be totally underwhelmed but after just a few questions I can tell that 5.1 Thinking is all I am going to ever use. Maybe it is just the newness but I quite like how it responded to my standard list of prompts that I pretty much always start with on a new model.
I really was ready to take a break from my subscription but that is probably not happening now. I did just learn some nice new stuff with my first session. That is all that matters to me and worth 20 bucks a month. Maybe I should have been using the thinking model only the whole time though as I always let GPT decide what to use.
From what I recall for the GPT5 release, free users didn't have the option to pick between instant and thinking, they just got auto which picked for them. Paid users have always had the option to pick between thinking or instant or auto.
For GPT-5 you always had to select the thinking mode when interacting through API.
When you interact through ChatGPT, gpt-5 would dynamically decide how long to think.
