Susysyay, I played the demo, and its not bad.
Level Design: Excellent. Partly because you made it make fpsc look limitless and good, and partly because you copied the design from BF:BC2
AI: Amazing, best I have ever seen in an fpsc game. You should, however, make the allies auto-follow the player. It isn't too hard to do.
Spawn Placement (enemies): Pretty good. For the second level, there is a part where they spawn, or at least are placed, somewhere behind the player. At the very least, I walked around a building and they were on the other side. This lead to me dying without a chance.
Storyline: For developing a game in fpsc, you did awesome. Great HUD markers for what to do, great cutscenes. The voice acting is a little rough, but that is fixable.
Performance: I am running on a cheap HP Laptop. I could still play it fine, although there were a few parts where I had severe dips. It probably stayed at a consistent 25-30 for the most part.
Glitches: I could climb the trees to get onto the walls. This really brings the game down. All you need to do is add a simple plane through the trees. Another easy fix.
Overall: Easily the best FPSC game I have ever played. It might not be original, but it proves FPSC definitely DOESN'T suck.