I got it as a gift soon after it came out. From what I recall the main menu did not support the mouse. I got to the third campaign and then didn't play any more. I played a little more last year after I GFWL became free to play games over it. It was a hassle setting up a GFWL account and they still had the a and b buttons on the GFWL menus(did they ever change that?). I had very hard time figuring out why I couldn't connect to GFWL, then I found out it was because I was running XFire(not joking, when I closed XFire, Universe at War could connect to GFWL and not before).
Of course, my campaign progress was gone, I think it may be required to be logged into GFWL to save it(never bothered to find out). I played one or two games singleplayer then quit and uninstalled.
I never got around to playing multiplayer.
I have to wonder what would have happened if Stardock had been the publisher(or just a better publisher in general).