Don't think I can say anything that hasn't already been said - the art and soundtrack are sublime, controls are perfection, gameplay is superb. I spent about 15 hours on this, 5 of which were on the bullshit dragon boss, and I had a fantastic time.

There's elements of luck in that spawns can be unfair in places, or you can can get good/bad patterns, but it doesn't drag down the experience. Absolute must buy.