I absolutely love my 21:9 monitor. I got the 34" Asus one with V-sync that cost more than I like to think about. The picture is gorgeous and very immersive... as long as you can get the frame rate up.
And there's the rub. My i7-2600k with 970's in SLI couldn't cut it with details cranked up at that resolution. My expensive monitor purchase directly caused a new computer build with a 1080. Now it's awesome, of course. Just be mindful of the CPU/GPU power you will need to run 3440x1440.
I also love it for every day and desktop stuff. I dock windows "full screen" to half of the monitor. It's like having 2 full monitors without the bezel. I greatly prefer it to my old 2 monitor setup.