Great game, great music and a great concept, but for £3.99 I expected a lot more game time. There are essentially three levels with three boss-style scenarios, which are all fun and challenging, but there isn't much more to acheive in this game. If you complete it the game, you get some optional mirror stages (with no checkpoints) to acquire all of the achievements, but after that the game is complete and there is nothing else to do. Never-the-less, I really enjoyed the way the game moved with the music.
I recommend this game, it is a good one, but I don't recommend you pay full price. If it's on sale, you should definitely add it to your collection, especially if you like rhythm and or platform games.