This game is one of the best, if not the best DS games out there. A must for any DS owner.
There are plenty of unlockables and awards to keep you playing this game even after you've beaten the campaign once or twice. Some of the new mecahanics in the game include Tag Powers, and dual screen battles which add a whole new level of depth to the game.
Pretty much the only gripe that I have with AW: DS is the fact that there could've been better touch screen use. The entire Campaign I played without using the stylus. On the other hand, the touch screen made it much easier to use the map maker / editor.
I had high expectations for this game after owning and beating Advance Wars 2: Black Hole Rising for the GBA. And I'm happy to say that AW: DS has met every one of those expectations and then some. So the bottom line is: if you have a DS and don't have this game, buy it, now. And if you don't have a DS, this is a very good reason to get one.