Help me understand

I was in the first .01% of users of chatgpt according to openai and an avid API user before that. I actually have a early beta of a openai API based chat app I was working on before chatgpt came out.

I see some problems with chatgpt that I have seen in it for some time but I honestly don't see how 4o was better. I've been using 4o as my main model for the past week and although it is quicker it isn't always better and when updating my vibe coded programs, 5.2 is much better at following complex instructions accurately.

Help me understand in which specific fields 4o is better