I like the combination of the turn-based, strategic shooting and the frantic reloading. I think in terms of mechanics this game is quite solid--made a whole game out of ammo management, and it's even good. :)
Some criticism: the sound is obviously at the bare minimum acceptable level right now. The way the bullets move as you reload them--quite floaty--moves this mechanic (which is excellent) a little away from building tension toward frustration. I think if this was very smooth and precise it would take nothing from the difficulty and simply enhance the experience of what is, at core, a cool gameplay loop.