I finally got around to peeking at this. I'll agree with pretty much everything stated above, and I'll point out a couple of other little things I noticed. They are pretty much small things, or else things that I'm sure you'd do anyway as you work more on it.
Not only are the walls around the beach area odd, but the walls around the last area are odd too... maybe if they were made with a concrete texture like the others, instead of a dirt one, it'd make more sense, but as it is it doesn't look right.
Adding to the comment about breaking up the areas a bit more... the beach area has a fair amount of stuff going on there... there's rocks and bits of cover and a fence... some detail, in other words. That's good. The other areas are pretty barren, with just a prop or two tossed in. Put in some more props, put a few decals or something up on the walls, make it look more like a military base of some sort rather than a few empty rooms with rockets in the back. I realize there's a lot of brush work and stuff back there, but it nonetheless feels like you spent a lot of effort on the beach and very little on the rest. Make the whole thing feel complete.
In the front room behind the beach, the lights are sort of hanging low. You can hop up on the pipes in there and jump right into a light, which is going to somewhat negate the effect of having any higher ground in there. You may want to just have them all up snug to the ceiling, or at least not quite hanging so low.
Finally, there are a few walls that are too thin. It doesn't affect gameplay or performance any, but if you're putting concrete textures on walls, they should have some thickness to them. There's a couple that look to be 1 unit thick, which would make sense if they were supposed to be glass or maybe sheet metal, but in this bunker, they look fragile and out of place.
In the broader scope, I think Youme has some good suggestions. I'd have to hold off until the next version, and actually play some matches in it, before I'd really say much else. I like the random explosions on the beach, though. :thumbup1: