So so good. I got sucked in and played for much longer than I intended, even if I had to die a whole bunch before I could even survive the second wave. Loved the artwork and main character animation. Would probably have enjoyed more visceral feedback when firing the gun (you know, a more realistic gunshot sound, screenshake, all that good stuff) but that's just me. Impressed at how polished this was--really felt like a complete game.
(edit) meant to say that I also wish you could upgrade between waves without having to die, but since you keep your money even after death I guess it amounts to the same thing.