First, let me say, I love that game (already told it in other messages).
Howerver, I find the interface design a bit simple. I mean, they are nice, clear and helpfull, but a bit old in style. Don't you think it would add to the title to integrate an interface design equivalent to the one found in RTS (C&C3 faor exemple, or Dawn of War).
It is, mind you, purely haestetical, but well, you have the potential to create such a hugh game ... could'nt hurt.