Same. I'm not an elisp expert by any means, so I tried using claude and chatgpt to help me write some functions. They got close, close enough that I could massage what they wrote into something that did what I needed, but they have never produced anything that just worked.
Not my experience. I've had them write modes for new languages from scratch with excellent results.
And diagnose and fix up my emacs configuration.
Even back in pre-Opus 4.5 days I found them incredibly useful for elisp diagnostics, and these days I use Codex to great effect to enhance my emacs setup.
That is not my experience. I had Claude add a variety of useful functions to my init.el as well as refactor it for easier maintenance. I now have a more useful to use and pleasant to edit init for it.