Not bad, but...
As it's been said, this game is really lacking for something. A storyline, the upgrades to weapons, more than three stages, any of these could help make this a great game. It has the graphics, especially the stills, which are beautiful.
Also, there are health packs and ammo, but they're random drops from kills that must be shot to collect (confused me when I ran to one and it never picked up), and seldom show up when you need. The strategy for beating the game isn't difficult either; you stay just within your range, which is just outside the range for every enemy in the game, and shoot whatever you have. I took out every turret and most enemies this way.
It's not bad, but it could definitely be a lot better.