I know it's a copout, but you have to see the video to appreciate the graphics. The graphics are perfectly in style with Advance Wars GBA, which is slightly cartoony but has a recognizable cool style.
The video also lets you see the gameplay, which also looks just like I'd hope an Advance Wars conversion to 3D would be.
You have to see the video:
http://media.cube.ign.com/media/676/676364/vids_1.html
(you may have to be and Insider to watch, so another link would be helpful)
Don't get me wrong, I realize the graphics aren't ultra-sleek realistic. But they're not supposed to be, and I like that.
This is now one of my most-wanted, and I didn't even know they were making it until E3!