I started playing the demo, and all I can say is: "holy crap!" First of all, its effing gorgeous. Screenshots just don't do it justice. And the commander and squad lead actions are really cool and inventive. When you get "killed" the first two or three times (I can't remember), you can call a medic and they'll fix you up and get you back to fighting, unless you like fall off a cliff or something. I'd say more, but now I'm going to go play it again.
Edit, there are actually times where you're jsut seriously injured, and when you're killed. That's what decides if you can get back to fighting or not.