When I finally took the time to play the entire game in one sitting, it was a real joy
The Gameplay is the real draw here. It uses a Smash TV style of gameplay (move with the left joystick and shoot with the right) and offers a few weapons choices, each with their own strengths and weaknesses. I usually favored the flamethrower as it seemed to take down enemy tanks and mechs faster than anything, but for stationary objects the cannon is devastating, and the mini gun is great for range or for mowing down swarms of explosive-laden kamikaze soldiers. Save the grenades and nukes for the bosses, as it's relatively easy to get by without them through the levels proper.
The Graphics are excellent for this type of game. Really, I think that in some genres you reach a certain level and then any more would be in excess. The mechs and other baddies are impressively detailed, and the terrains are actually sometimes quite lovely. Nice details like enemy tanks crushing down trees help make this familiar type of game seem fresh. The Sound is where it should be, nothing too out of the ordinary. Though I do enjoy the high pitched wails of the kamikaze boys.
The Achievements are mostly reasonable. They primarily revolve around beating levels with different restrictions, i.e. don't use any grenades, destroy over 80% of your opponents, etc., and can be gotten by playing the first zone over and over again. A few of them can be very difficult, and even though I've finished zones with 73% accuracy before, for some reason the "Don't waste 30% of the bullets" achievement still hasn't unlocked for me.
I'd say this is probably one of my favorite XBLA titles so far, if not my favorite. When I finally took the time to play the entire game in one sitting, it was a real joy. I'd recommend this to anyone who's ever enjoyed an old-fashioned shooter, and if you've never played one (you young'uns), this is a superb introduction.