I've been using Atom full-time for about a year, after switching from Sublime. I'm happy with it as an editor, and like the momentum behind the plugins ecosystem. Performance has been completely adequate, and I've seen none of the issues that always seem to crop up whenever Atom is mentioned on HN. There may be a platform difference - I use it on OSX, but friends of mine on Linux have been less satisfied.

I do still resort to vim on the command-line for some things, but as a "daily driver" code editor, Atom has been excellent.