Take a look at my first HL2 DM map....called dm_inbound , a large dark map, built with blood and sweat, a real man's map with secrets and a nice trap (see if you can find it) Has taken a long, long time to make and optimized as best as I could.
I purposely made it a dark map (actually the screenshots show it to be darker than it is for some reason) for the idea that it can be played stealthy with plenty of hiding places. It makes a good TDM map, as certain areas can be controlled, however it is a pretty big map so you may need a fast PC to run it with a few players.
Enjoy...
You didn't state for what player count the map is intended but it looks like quite some players could fit in. I think it's too large for 8 players but with the current fps too many players might be a bit of a problem. Playtesting should tell...
I noticed a lot of items are somewhat hidden or placed next to explosives or are otherwise placed in hard-to-get area's. Maybe that works well, but personally I think with the already large nature of the map it's not a real good idea. Armor and a weapon are best quickly accessible from the spawn point so you aren't chanceless against an opponent who's running around for a longer time and stocked up on weaponry already.
So, I like items and weapons to be somewhat easier to get. The more heavy weapons or a real fat item storage room are best made hard to access so their power doesn't come at no cost, but the more basic stuff should be available sooner and easier.
As for visuals, I already said I like the details and especially the sounds and all. They're nice touches, like the man screaming for help. Some textures weren't chosen that well though, like some walls had a generic metal texture that's probably meant as a floor texture. The outside area's looked great though.
The level is also easy to learn despite it's size and I think you've used the vertical axis great. One note about that though: a player that's on a higher place has an advantage over lower players. He doesn't need cover but just has to step back somewhat to be safe. The lower player will have less use of cover because of the height, too. I noticed you placed some AR grenades on the roof. I think that's outbalancing things somewhat: the lower player could use some grenades to counter the height difference rather than the other way around.
All in all, overall it looked great and the ambience was well-done, but the item placement and size could be done better.
Have you playtested this map with others throughout the construction period, bytheway?
And with such a big layout, it felt strange to walk in spaces of minimum with like pipes.
Good job anyway. I hope to see more maps from you.