No, it still fares very poorly when matched up against ST3 (or Textmate 2, or basically any high-quality native editor). It is slow slow slow, and has lots of little quirks which are clearly a result of the wacky way they decided to build a text editor.

BUT.... it is way, way better than it used to be. I keep it installed and use it from time to time, to let it update itself and see how it has grown.

It clearly has momentum, and computers clearly are getting faster... probably one day the slowness of it won't matter. But it still matters today -- Atom is noticeably slow on the fastest Mac notebook you can currently buy.