So my only complaint about the UI so far while playing is the level up screen when you learn new perks. The primary red/blue/green backgrounds with white text are awful to try and read since there is no contrast (green especially). It would be nice if we could see some graphical update to make those colored bars look more like the rest of the UI and less of an eyesore.
I made a little mock-up of what I think would improve the readability and to match what is used already on those screens.
And a link to the PSD mock-up if you wanted to look at any of the styles:
You don’t have to use this by any means, but I wanted to suggest something that could improve the readability of that text (I deal with this stuff every day so it sticks out to me).