Smooth gameplay, fun and simple graphics, nice subtle use of effects. All in all a blast to play.
However, I came across a problem that's pretty annoying. Upon "killing" a boss it started waving a white flag saying it's dead. Now, for all intents and purposes, a defeated boss should -not- be able to hurt you. But as I was zooming around waiting for it to disappear I touched it and died.
C'mon, :P how can a defeated boss kill me?
That's my only complaint! And one that should be fixed! :D