There are several things, that i think will make the UI better:

1st - Color change and menu shape.I think all that grey/black choice of colors for the main page is not that good.I nice mixture of other colors would make the overall look so much better.And all that square and rectangle shape of all the menus.It's like you are navigating through some boring software editor program or something like that.This could definitely use some improvement.

2nd - In most games all the menus in the main page are semi-transparent and you can see some background picture behind(of course this would require some nice background picture or 3D animation).This will make huge difference and again will make the overall main page look better than the current one.

3rd - More detailed profile page.Stats,kills/deaths,XP/gold per min,achievments(when they are implemented when the game is released) and so on.

4th - New loading screen art.Not related to the UI, but nevertheless i will mention it.

Thoughts?