I like the different elevations. When I was halfway up to the top there were guys shooting from below as well as above. That was cool. Maybe spawn the player in the middle? I like being able to jump to the different platforms. Maybe put some pickups (megahealth or whatever) on some of the platforms to entice the player to get there. It is also a risk vs reward thing because falling damage is brutal in this game.
Caution: When I was at the top there was nothing blocking me from seeing the entire map and all the guys running around. I am running a pretty beastly machine and framerates were around 55 or 60. This isn't bad but you haven't even begun to art this map out yet. I would seriously start thinking about some VIS blocking structures that will make sense with whatever theme you are going to run with. Also, having more than 5 or 6 grunts active at once starts to hit the framerate as well.
I could see this as a rooftop battle in a run down city. Dirty alleys at the bottom. Could be cool.
Art it up! I think it's a fun start.