I definitely had to use the easy mode unfortunately XD I loved it, and the mechanic of adding powerups to your rhythm (and hearing it) was really really neat! And it was a neat visual touch that everything pulsed with the rhythm even in the menus!
I can't say I chose powerups with much thought, I'm sure there are some really great synergies but I reckon I'd have to play it a few times to start picking up on how to properly choose and arrange powerups to get the most out of them.
Great game, well done!