Earlier quoted context omitted.
Yes, this is very much my experience too. Switching to GPT5 Thinking helps a little, but it often misses things that it wouldn't when I was using o3 or o1. As an example, I asked it if there were any incidents involving Botchan in an Onsen. This is a text that is readily available and must have been trained on; in the book, Botchan goes swimming in the onsen, and then is humiliated when the next time he comes back, t…
I feel like the value of my plus subscription went down when they released GPT-5, it feels like a downgrade from o3. But of course OpenAI being not open, there is no way for me to know now.
I'll play devil's advocate and say that I think the Codex-cli included with the plus subscription is pretty good (quality wise). However, after using it, it suddenly told me I couldn't use it for a week out without warning. Claude is a bit more reasonable there.