Sure. It does lots of research, especially for math papers and things that I'm unable to find like repair manuals, published numbers, things like that. It explains the math / algorithms to me (for example, I don't know calculus very well at all, so I need handholding). In terms of "how much of the code does it write," I don't have a percentage for you but generally if it suggest something to add to the testing suite I will allow it and if it wants to make changes based on a code review I will allow it. For bug hunting or "why doesn't this sound right" analysis, I make audio files (say, a guitar recording or a drum loop) and have the AI analyze deltas so it can give me information about what might or might not be happening. There are only two people working on this, so we let the AI keep track of roadmaps (like if I get an issue on Github or a comment in this forum, I might say something like "don't let me do a release without addressing this: [comment]" or "remind me that I wanted to research such and such." I'm a software engineer as my day job, but I'm sure that I would not have been able to do this without AI. I understand that AI can be a touchy subject and that's why I chose to not charge anything. There are a couple of other audio-related things that I haven't put out yet that are almost entirely AI from start to finish.
I hope that helps and doesn't turn you off too much.