I have a 21:9 display, the LG 34UM95. Overall I like it, but I wish I had gotten the curved version (I think). It's so wide that I find the edges a little bit unusable for full-time stuff. It's nice to keep notes and things off to the sides.

I went this route because I didn't want a 3-monitor setup, and a 2-monitor has the bezels in your direct view, or one monitor off to the side. My current setup is the 34UM95, and a 24" Apple Cinema display (on a different machine) directly above the 21:9 display.

The curved version has come down a bit in price, I may try swapping to that.

Yes. I like it much more than a dual monitor setup. I also tried 4K monitors and at 27" it's just too small for my eyes. I need to scale up everything anyways so I am essentially getting a 27" 1440p with smoother fonts and more image retention issues. More screen space on the other hand is real and useful right away.