Just installed the demo, it will run on my machine but I'm not sure which settings.
EDIT: Had mostly low with some mediums, ran at 38 FPS most of the time. It's quite good. A worthy successor to Far Cry, I LOVE the physics. Also really like Crytek's putting of animal life in, like turtles, crabs, birds.
The AI isn't bad but I didn't let them live that long anyways so I didn't test that out. I love the suit and abilities though I wish I had a bit more energy but it keeps it from being TOO uber.
Though, maybe because of the story line, it's not the whole island is open to you but like Far Cry there's lots of space for most of it so you can take a few different paths (well, land, water, or a combination) you can also avoid most of the enemies if you want.