Loving this game. Played it through to completion on Normal and man, it's hard. Can't imagine what the actual Hard difficulty will be like. Died countless times on the end bosses of levels 5 and 7.
Replaying on Easy now, to pick up on some of the nuances of the scoring system.
Also, to those not sure about the graphics, you really need to play it to see just how much stuff is flying around at any one point in time. Actually quite impressive.