I've used it for a while. I think the ecosystem is great. I don't have too much of a gripe for the things that most do (slow startup, can't handle large files). However, there's a bug with full screen on OSX that is a deal-breaker and keeps sending me back to Sublime: if you swipe between full-screen instances of Atom, sometimes modals end up in the wrong place, but you can't get to that instance. So you have to hard-kill, and imagine if that modal is a Save As. (the other day it did something differently strange and annoying: Have 2 projects, A and B open. Swiping between full screens, it only showed A.. only way to get B was to select from Window menu, and this behavior kept persisting whenever I'd swipe away)