I've been using Gitter for a few months now, I think it's just polished enough to use consistently. If it were even slightly unstable I'd have to stop using it.
But Gitter has other issues - mostly of the UX kind. One of them is that you can search for other rooms, but you can't really save that search. You have to start over everytime. Also, the default of sending you an email for every freaking message when you star a room is absolutely atrocious.