Using it on and off, but that's mostly because I'm hopelessly addicted to vim. In fact it says a lot that this is the first editor that can replace vim for several days in a row.

Coworkers otherwise completely replaced Sublime with Atom.

That said, atom can do stuff that is simply impossible to do in vim†, such as https://atom.io/packages/svg-preview (shameless plug).

† used to use vim+fswatch+open(1) on OS X, but that's incredibly hackish in comparison to what amounts to instantaneous native support by design.