I played it on the specs found in my signature, minus the GeForce 8800GTX. I replaced it with an ATI Radeon HD 5770. Running everything at highest, DX11, 1680X1050. Mine certainly chugged a little, averaging around 30FPS.

This game will push your system like Crysis did (does).

As for the one gun, there is a surprising amount of depth to the one gun. You'll have to learn how to use the gun as a propulsion device, and counter the movments it makes for you when firing. There is good potential for 'advanced techniques' with the gun.

Potentially, if you power down suit, catch the spash off of a concussion nade, then fire your gun in the direction of the blast, you can move in speeds greater than your boosters. That's one example.

The game is only a few decades into the future, so from a viewpoint of realism, you woulnd't have much more up in space other than an automatic rifle. Realistic isn't always fun though. I would like to see the weapon loadout expanded in some way, but I really, really enjoy playing it as is right now.