Congrats to the team for reaching this important milestone. I'm a Sublime license holder, but I use Atom as much as I can, because the more open source can win, the better. However, yesterday I was doing some complex regex's (porting a random sql dump file into a seeds.rb), and Atom kept dying, whereas Sublime was pretty much instantaneous. I'm not doing the usual "Atom is slow" drum beating, but saying some underton…
http://i.imgur.com/McaVhKJ.png?1
The menu has no margins and no padding but, worse of all, everything is tiny. Note that the main text font is smaller than the i3 top bar (which is at the barely readable size).
HiDPI support is not something esoteric nowadays. Lots of hardware requires it, and Linux toolkits support it rather well (not perfect, but ok anyhow).
I fiddled with Atom's CSS enough to test drive it. It is ok for common tasks, albeit a bit sluggish (I come from vim...). I could live with that. What I can't live with is all manners of breakage my custom CSS introduced, so I can't yet do a one month run with the editor to kick the tires.