Just yesterday, I wrote a first version of a fairly complex method, then pasted it into GPT-4. It explained my code to me clearly, I was able to have a conversation with it about the code, and when I asked it to write a better version, that version ended up having a couple significant logical simplifications. (And a silly defect that I corrected it on.)

The damn thing hallucinates sometimes (especially with more obscure/deep topics) and occasionally makes stupid mistakes, so it keeps you on your toes a bit, but it is nevertheless a very valuable tool.