It won´t be your primary game, but can be fun at times.
The graphics are not bad. If anything, they are up to what you would expect in this kind of quick game. The aliens are not original, that´s true (they remind me of a movie that I don´t really recall the name... It had those insectoids that looked like spiders, much like in this game, tough they were yellow) but they are fun to blast, and there are a lot of variety along the levels.
The sounds in the game will not be anything memorable tough they do what they come to do and they do it right. You won´t be offended by them (at least not as much as I was offended with the voice acting in Baten Kaitos. THAT was mediocre...) but won´t be awed either.
The game play is easy to understand and easier to get along. You will have no trouble dodging bullets and firing. Pretty much you press L to roll left and R to roll right. It´s intuitive and easy. At least the controls won´t get in your way. The worst thing in a game is when you need responsible controls and they aren´t easy to apply. It´s not a concern here, tough.
The levels are increasingly more difficult tough since you have infinite continues and you continue from the very spot you dropped, it makes the game that much easier (if not ridiculous) to beat.
Multiplayer in this game is fun to bring a friend and blast aliens together. Since it does have a score board, it makes that much fun to try to beat someone high score (and yes, I like to try XD).
In the end, when all is said and done, you will still be back, sometimes, for a quick blast trough the levels, to see if you can try and beat your old score or when you´re too tired to think and try something more difficult. It is somewhat relaxing to beat aliens to a pulp at the mere press of a button at the end of a stressing day. =)