Although bashed for several reasons (most wrong, in my opinion), I find this game interesting and absorbing.
It was originally bashed a lot for its "blocky, sloppy, and overall bland and ugly" graphics. However, I think they fit the game. The appear somewhat gritty, and when you're out on the battlefield, what would you expect? It just fits. The bland, barren ground and sides of mountains adds to the experience, I think. It makes everything look the same, and maybe I'm just crazy, but I think it goes well. I wouldn't use that as an excuse for poor graphics for other games, and honestly, if I were making this game, I wouldn't have gone for this style graphics. But as a result, it just seems to fit.
The controls were another big problem among critics. You use the DS face buttons to look around, the D-Pad to move, and the right trigger to shoot. The left trigger will use your jetpack, among other things. You use the touch-screen to exit/enter different tanks and mechs, and switch weapons on the fly. This, of course, is merely the default controls, and you CAN change them in favor of a different scheme, but it works for me. It does take some getting used to, but you're not going to go through the whole game thinking "I can't figure out these controls". Occasionally, though, I did mess up by trying to look up, and in reality ended up looking down, but that's more of a blunder on my part.
The action, however, didn't receive as much damage from the big boys. The game is relatively easy (although frustrating for all the wrong reasons - cheap deaths, lame minigames, etc.), and you shouldn't have to try any level more than a few times. Once you go through the level a few times, you'll get a picture of where the enemies are and it shouldn't be too tough from there. The fighting is simple and straightforward: shoot them before they can shoot you. There's really no strategy involved, other than deciding if you should use your jetpack and shoot or just stay on the ground. It gets repetitive after a bit, and that can be a bummer, so the game is probably best played in short spurts.
The sound, although not that noticeable, was decent. There was voice acting (really corny voice acting, but it was there, and there was quite a bit of it), and the sound effects aren't bad. It's a pretty self-explanatory game, and it doesn't do anything out of the ordinary, so the sound shouldn't be a big problem. Half the time, I play with my DS's sound turned off (or way down), so I'm not big on the sound capabilities of the system.
There was a slight letdown in the multiplayer, though. It's basically just multi-cart play between you and your friends, but I'd doubt it if 3 of your friends had the game. It would have been a lot better if there was online multiplayer, but it wasn't really needed. It might also do you well to check out the actually helpful help file ingame. There's a lot of content and it was nice to have when I forgot how something worked or just wanted to look things over so I was prepared. It was most certainly a pleasant surprise.
Unfortunately, in general, I can't say the same thing for the actual game. It's decent, pretty straight-forward, and it's all been done before (then again, a lot of the DS's games have been done before). It didn't really do much that was horrible or completely awful, but a few issues made this game worse than it should have been.