Just going by the screenshots:
- It looks like the map wasn't vised. There's no reflected light (that or my monitor here is just too dark - but some areas look pitch black, like the bunker in the first shot). Maps MUST be vised before being released, even as beta.
- The light texture is misaligned in the second shot. Also, the side of the light has light textures on it, too, which looks bad. Typically what I do is create a brush with the metal texture aligned on the 32x32 grid, then apply the light texture to just the bottom face. It will already be aligned since I used the grid. Press alt-l to lock it, and move it wherever needed.
- The barrels aren't phong shaded. If you grab the latest BSP pack, they should be automatically. This helps them look less blocky.
- The map itself is very blocky/square. If you're using rock textures for walls, the walls should look like rocks. Clipping planes are your friend here. You can whip up some convincing rock surfaces pretty quickly by adding some brushes and slicing chunks off of them. For large areas, it's probably better to make the map less square, too. Even some slight variation can make a big difference in the visual appearance.
- Bunkers are unrealistically big and thick. Pretty much every paintball2 map suffers from this. Try to give your map realistic proportions and believable environments. Would you see 10-foot tall bunker made out of a 3ft thick solid block of wood with a hole cut out of the middle on a real paintball field? Probably not. It would be made out of some cheap plywood and 2x4's or something.
- The lighting is rather random and unsourced. There are just splotches of light scattered around the map coming from some mysterious, unseen location.
