The idea isn't new but it's executed rather well. Having the player move as quickly as he does with the physics helps out greatly.

Some issues: 1. Basically the only weapons worth using are the SMG/shotguns; when you can fly, the grenades and rockets are entirely non-threatening. But... 2. There isn't nearly enough ammo for anything on this map. It's a huge map, but with myself and $lave we had trouble finding ammo. This is not good. I would also have some ammo floating around since no one will actually be walking on the ground normally. I think the problem lies in the item respawn rate, so I direct you here: http://www.pfhorums.com/index.php?showtopic=2403 3. The texturing is generally okay, but you greatly overdid the flickering lights. Static lights are quite fine. Generally speaking, the contrast is fine, so I would just get rid of most of your flashing and flickering lights; they're very annoying. Also, in one particular area you use the same light panel texture on almost every wall, which is really annoying. 4. This level is absolutely enormous and most of the side rooms are completely extraneous. In addition to its size, the multiple pits and the messed-up radar make it very difficult to find someone who's hiding. Uncheck the Magnetic radar setting. 5. Getting rid of that water fader is really important. I would embed mml to remove the fader entirely. On that note, merge in the physics, because the level is absolutely dependent on them.

This is a pretty tired idea but probably the best execution of it I've seen; it's just rough around the edges. Fix these listed problems and you would have a solid map.