I have the Dell U3415W, which has the same resolution and size. It's probably the same panel, but it doesn't have G-Sync. It cost about the same as this one, too.
I have had problems with it because of the high resolution and wide aspect ratio. WoW runs fine, but the game is distorted on the far sides, giving me a less effective field of view than I expects. Most games and movie playback software won't run at anything more than 2560X1440, wasting the sides of the panel. Star Trek Online won't even run unless it is in windowed mode, and narrowed to the point of effectively being 2560X1440. It won't run in full screen 2560X1440.
I advise staying away from 21:9 screens for now, until software developers get used to the idea of them being out there. Otherwise, they're no better than a 2560X1440 screen.