The textures need variety. Why are parts of this map 3+ world units tall? The teleporters should relocate their destinations. Lighting? As far as layout goes I would recommend limiting weapon choices to dual wield shotguns. Small groups of 2 or 3 only for optimal enjoyment.

Variation in floor/ceiling heights is present. At this point, we're at an M1-level net map. There's plenty of room for improvement, though. It's good to see that weapons and ammo have no problems.

The map is still very cramped. For any more than a two-player duel, three-player at a push, the gameplay would deteriorate.

Please raise the headbanger ceiling in the center of the map.

There is also little variation in lights, giving the map an appearance without volume. I recommend you play some popular net maps, or even solo scenarios, to get an idea of differential shading.