i have been using it for 3-4 months now and its getting there each month. Sometimes the plugins fail but this could be because of the rapid development cycle of atom.
On the positive side, its a good text editor, easy interaction, plugin install super easy.
A downside is that its not easy on your ram though. Consumes more than what vim would do. But overall, if you need a modern editor, this is the way forward.
How well does it support other languages other than JavaScript? Will I be able to do mobile Android and iOS development at some point, or Haskell, Go, etc?
Facebook has built a set of plugins for doing just this. It basically turns Atom into an IDE. Haven't tried it myself but from the videos it looks nice.