I'm still playing through this, so I can't exactly call this a complete review -- but from what I've seen, it's amazing. :D
For starters, the moving and aiming system work together well (move with W, S, A, and D, shoot by pointing and clicking), and I was surprised at how easy it was to pick up. The graphics are just fine for a top-down game like this -- the people don't look too amazing (the character you play as included), but the environments are surprisingly detailed, including the little scraps of paper you walk over during the course of the first level (as an example).
The music was awesome. I happen to be a huge fan of MaestroRage here on Newgrounds, so I was smiling even though the song is sort of down and you're killing people.
My largest problem with it was the menu, which didn't really tell you when you'd pressed a selection -- for example, when I pressed a different crosshair button, it changed the crosshair, but didn't have any sound or something confirming I'd pressed the button -- normally a clicky sound would be a nice touch. :P
It was a great job -- and I look forward to the next installment. :D