I've been very close to purchasing the Asus PG348Q, but it'd be nice to hear some advice from a good community such as this one.  Would you recommend 3440x1440?  From what I've seen, the only display that could possibly rival this one for me is the 4K 144Hz monitor Asus is planning on releasing next year.  I currently have two 980 Ti's and I will be upgrading to two of the next Titans, so GPU horsepower isn't much of an issue.  The only drawback I see is thew 100Hz cutoff.  While my 980 Ti's probably won't hit that mark for most modern games, two Pascal Titans will probably crush this resolution.  Let me know what you all think.  We can even turn this into a discussion of the current state of 3440x1440 as well as its future.

I use the Acer predator x34. which is 100hz g sync panel. I absolutely love it. I have 2 980ti's and most games (that support this resolution) it stays pinned at 100FPS on max settings.
 
This is likely going to be subjective though. I found that anything over 100FPS I cant really tell the difference especially with a g sync chip. This is not the case for others.  FPS and fast paced shooter gamers seem to appreciate/notice the 144hz more not the case for me. 
 
I didnt go 4K for two reasons. 1st is the horsepower needed to power this at what I am now used too ( I cannot go back from 21: 100FPS) will likely be still difficult to attain for the next few years and increasingly so for future AAA title until all the tech catches up with monitor resolutions. This is just my opinion.
2nd in game the difference between 3440 x 1440 and 4K  seemed hardly noticeable for me. maybe this is just my vision? Also there is DSR with NVIDIA cards that can achieve 4K on normal panels. Some people hate the way this looks. I kind of like it.
 
My suggestion would be to find someone or a store that will allow you to game on both resolutions and see which looks best for you.       
  

This is true some games do not support ultrawide. I came from surround setup so for me even with the bars and 100hz cap its perfect. For you it may not be. 
 
Again this will be subjective and you should test yourself to see what you like best. 
 
Ultrawide is awesome though. For me so much more immersive. 

I went with the PG348Q ($100 off from Microcenter) and I'm enjoying it.  For games that utilize 21:9, it's great.  It also has put my multi-monitor setup to rest for productivity.  Don't worry, I'll probably still get a 4K 120Hz+ display next year ;) 

I have that monitor.  I will make this easy:  yes.