I'm not sure if it's been brought up already, and if so I apologize.
Few things though:
1) It'd be nice to be able to "unbind" what is done by default. I realize it's probably setup by default for people with the x-box controllers, and that's fine, but if I could make an empty bar and put what I want, where I want it, that would be awesome.
2) It'd be nice to have a "lock" button on the UI so that it doesn't move when moving the mouse around. I'm constantly moving my mouse around and I'll go to click something and accidentally drag my chat box half-way across the screen.
Overall, I actually like the way the UI is designed, it just needs a couple of tweaks and it'd be perfect.