For adding and refactoring it can be a great tool. For greenfield development, it's more tricky - yesterday I sat down and started writing something new, with no context to give Copilot. Mid sourcefile, I paused to think about what I wanted to write - it spit out three dozen lines of code that I then had to evaluate for correctness and just ended up throwing away. I could have probably helped the process by writing docs first, but I'm a code first, docs second kind of guy. Totally sold on LLM written unit tests though, they are a drag to write and I do save time not writing them by hand.

It's going to be a bit before LLMs can make an app or library that meets all requirements, is scalable, is secure, handles dependencies correctly, etc, etc. Having an LLM generate a project and having a human check it over and push it in the right direction is not going to be cheaper than just having a senior engineer write it in the first place, for a while. (I could be off-base here - LLMs are getting better and better)

I'm not worried about being replaced, my bigger worry is in the mean time the bottom end falling out of the engineering market. I'm worried about students learning to program now being completely dependent on LLMs and never learning how to build things without it and not knowing the context behind what the LLM is putting out - there's definitely a local maxima there. A whole new "expert beginner" trap.