Absolutely devastating!
I bought Beat Hazard on a whim, drawn to the promises of music inspired gameplay. Being a musician this sounded like a great idea, but I honestly didn't expect much more than something i would play for a good 30 mins or so and probably delete from my hard drive like so many other games on the arcade. I was pleasantly mistaken.
Beat Hazard is a wicked game, especially considering it's indy roots. Sure there's not alot in the way of variety enemy-wise in the game, but then it really doesn't much matter. The waves come in surprisingly differing tactics that never cease to be a good challenge, and the concept of having your weapons fire altering real time in synch with your music is amazing and adds a lot of replay to a very simplistic game.
Personally I'm hooked, Beat Hazard is like video game crack if you love music, and any fan of space shooters will find alot to love here as well, even if your enemies and surroundings dont change much.
Great game, if nothing else download the trial, you won't regret it.