I've found it useful for getting features started and fixing bugs, but it depends on the feature. I use Claude Sonnet 4.5 and it usually does a pretty good job on well-known problems like setting up web sockets and drag and drop UIs which would take me much longer to do by hand. It also seems to follow examples well of existing patterns in my codebase like router/service/repository implementations. I've struggled to get it to work well for messy complicated problems like parsing text into structured objects that have thousands of edge cases and in which the complexity gets out of hand very quickly if not careful. In these cases I write almost all the code by hand. I also use it for writing ad-hoc scripts I need to run once and are not safety critical, in which case I use it's code as-is after a cursory review that it is correct. Sometimes I build features I would otherwise be too intimidated to try if doing by hand. I also use it to write tests, but I usually don't like it's style and tend to simplify them a lot. I'm sure my usage will change over time as I refine what works and what doesn't for me.