I finally got around to playing this (after the download finished 2 weeks ago, lol), and this game is awesome. The character graphics are a lot like Wind Waker's in the sense that you'll eventually get used to them. I marveled at the nanogun is despite it being a single colour.
Took me at least 4 hours to finish, too. I think closer to 5 because I died and then it reset the in-game clock to my last save. I almost feel compelled to play it again, too. And then speedrun it after that.
The story is well thought out, too. I mostly want to go back through to see what the different kinds of story permutations there are. (I killed everything in my way unless I was low on health.) The ending left me kind of happy and kind of sad and a bit disturbed. The credits downright angered me because after being forced away from the game (damn you, AIM!) I couldn't Alt+Tab back to see it; I could hear the music, but not the credits. I eventually had to kill the process itself.
Speaking of music, this has a great soundtrack. It gets a little stale and repetitive after 30 minutes of bad loops, but the first 10 minutes in hearing each track was great.
I might write a real review after my next playthrough.