Everything but perfect.
I absolutely love this game! It's an excellent action game and has great music too! But there are two things that keep it from being perfect:
1) The game freezing after the third level boss, although I'm this'll be fixed in the future.
2) There isn't any "Mercy Invincibility." For most of the enemies, this isn't a problem, but when I land in lava or get hit by a fireball I end up bouncing around and taking even more damage. If I land in lava, there's no way I'm going to get out before I lose at least half of my life. It reminds me of the "Spike Bug" from Sonic 1.
I really can't wait to play more of this game! I hope there's a sequel planned for the future.