That's interesting. My experience with Sonnet 3.7 early this year was pretty poor: It simply couldn't reach the correct solution alone, even when explaining the issues explicitly. The proposed invalid solution was not too far from the correct one, so you could fix it manually if you knew what you were doing, but then the way the code was structured was not something that I would like to maintain in a real project. All this on top of the usual UX issues like hallucinated APIs. The experience refactoring was even worse.
I guess your mileage is highly dependent on the domain of your problem? In my case was GIS by the way