It is very impressive. However, the fact that it manages a buffer of something like 30k tokens (or whatever new limit it is) means that it's definitely autocomplete and not something with reasoning. There will be a lot of things it can't do because of that limit. That limit will also increase the amount of forgetfulness GPT4 applications have because companies using it will "auto-magically" work around the limit by sending different chunks of history to it to get whatever from it. That also means that GPT4 applications will generally be architected to have that limit - which means weirdness - non-coherent completions or code generations that "forget" something important.

This is very different from real reasoning that has unlimited (yet imperfect) memory.