While often being unfairly compared to Geometry Wars, this game can certainly hold it's own.
I do like how the game tries to keep you busy for quite some time. The game has 89 levels, two play modes, and unlocking all of the difficulty levels can be very addicting. The achievements are nicely laid out in that they are challenging, but not impossible. A couple of them are VERY time consuming, so if you want all two hundred be prepared to play this awhile.
The graphics are pretty good for a Live Arcade game. It has a very psychadelic look to it, which is kinda cool. The sound effects are pretty basic and this is a game you might want to have some burned music going while playing.
My only problems with the game are the price ($10) and it takes WAY too long to unlock the difficulty levels. The price point is really puzzling, since all of the other dual-stick shooters available (including the excellent Geometry Wars) are only $5. That's not to say that this game is a bad deal, by any means. For $10 this game has already offered me more playtime than some of my retail titles have.
If you are a fan of any of the dual-stick shooters on Live Arcade or a fan of shooters, in general, you should really check this out. If you are unsure about the $10 price tag, then give the trial version a shot and see what you think. Just make sure you have those Microsoft points ready when you get addicted and have to download the full version.