Pretty cool once it gets amped up in the later levels (past the first upgrade), but it is a bit long and boring to get their initially, potentially leading to dropping off. Mechanics can be a bit frustrating as well without being able to aim the gun at all and being forced to wait, though I understand that is the main conceit. Still, once it gets going it is has a nice, challenging feeling to it with a good level of polish and creativity in the level design.