I've been playing this with a friend on Quest co-op, and it's amazing. I love the visual style and... basically everything about it. The sequel looks a little less like my kind of thing, but I've got a *teeny* wish for this version: I'd love to be able to see me and my friend's scores and kills either in real time, or pop up at the end of each section.
It'd keep things nice and competitive. We're always unsure who did most damage until after we've both died.