Sure, here are around 40 of the most obvious places to address.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10000.jpg
More light here: some suggested sources.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10003.jpg
More light and a window suggestion + light source suggestions.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10009.jpg
Needs more light, here are some suggested sources.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10021.jpg
More light, and some suggested sources.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10001.jpg
For a room that is largely secluded the walls are particularly bare. Exploit the fact that this room is cut off from much of your map by adding in more detail on the walls such as truss beams, cabinets, mops+buckets and/or corrugated iron sheets leaning against the walls.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10002.jpg *** use for ref
This corridor is boring, no 2 ways about it; and since it's an area where players travel more than fight you should include higher than usual levels of detail since players aren't distracted by combat/unseen threats. Include windows, diagonal trusses, ceiling pipes etc.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10004.jpg
reference ***
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10005.jpg
These are all plain walls seen from the gameplay area, i moved back out of the play area a bit to get more walls into one image. You should add more windows around here.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10006.jpg
Add windows and chimneys.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10007.jpg
It's always good to have window positions on the inside as well as the outside.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10008.jpg
Your 3dskybox cliffs are blocky and mostly unrefined. Add more rock props. I've also highlighted the horizon, you should add more rocks in the distance, the horizon feels very abrupt. Having rocks further out allows players to feel in a larger environment as as they move around the closer objects displace more than further ones.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10010.jpg
Reference ***
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10011.jpg
Windows plzkthx!
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10012.jpg
Hazard strips don't make much sense outside of an objective or death pit context as they are primarily used as gameplay devices. You should replace this with a basic wooden trim, it's quite confusing otherwise.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10013.jpg
Because this shadow doesn't translate to the 3dskybox your low z-clipping pane is quite obvious around this part of the play area. I wouldn't recommend extending it as it appears to only occur here, but it would be in your best interest to address this in one way or another. It doesn't look like much of a big deal in the screenshot but it's way more intrusive ingame, as you move around.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10014.jpg
These block shadowed walls are kinda boring, particularly since they're the background to a capture point. Add some light source such as flood lights with light beams hitting the CP or a small light illuminating the B sign overlay.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10015.jpg
Needs trims and supports, it looks really odd and unnatural otherwise.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10016.jpg
Windows and chimneys are a good idea. Chimneys break up the chunky horizon formed by a bunch of plain slanted roofs and add a vertical element to the horizon.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10017.jpg
Windows plx. Also, you have a missing texture (under the roof sheet in the centre of the image) as a result of over-zealous skybox culling. Use a displacement to allow the entire face to be rendered through the skybox brush.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10018.jpg
Windows and chimneys plx. Also, there's no reason for these props to have such a low fade distance, the room is well optimised, you can afford to stretch that distance by 128-256 units or how ever much is necassery to allow them to be rendered as the player turns the corner.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10020.jpg
Maybe this is just me as a mapper but these shadows show a clear difference in resolution. You should match these lightmap scales. Also, put a window around where i marked.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10022.jpg
Move the ammo drop away from the wall some so it's easier for players to grab and add some details on the wall behind it. Since the ammo drop will attract a lot of player traffic it makes sense to use detail here.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10023.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10025.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10026.jpg
More details on the walls!
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10028.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10029.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10030.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10039.jpg
Trims!
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10031.jpg
Inconsistant wall materials. This is just kinda lazy, split those brushes up so you can seperate the top and bottom materials and use a single texture for the interior, it'll be well worth it for the refined result.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10032.jpg
You have a number of shadow issues around the map, this is one of the 2 or 3 most offensive ones. Decreasing the lightmap scale can allow the face to recieve a full luxel of light data and illuminate these truss beams.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10041.jpg
Again but for the steps, make sure the steps recieve a full "dose" of light.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10033.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10034.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10035.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10036.jpg
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10040.jpg
Bushes go here!!!
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10037.jpg
You could do with more rocks, or a displacement batholith or some such detail here. It's proximity and visibility from the play area kinda warrants it.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10038.jpg
Windows, wall detail...
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10042.jpg
Again with the 3dskybox, the proximity and visibility from the play area warrants a slightly greater level of detail. Brushes smaller than 32 units don't convert well to 1/16th but you should add some roof details, maybe a concrete foundation as marked, etc.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10043.jpg
These faces wont be rendered from the play area anyway so culling them only saves neglibable light data and a little compile time, but why i point this one out is that it's visible to any play that falls or gets pushed off the edge at the blue marked areas. I'd suggest texturing these faces.
http://dl.dropbox.com/u/1429764/upland/cp_upland_rc10044.jpg
Chimneys, pipes etc.
Whilst you might counter-argue about potential negative effects by over densitisation (if that's even a word) of detail it's still important to utilise at least the windows and chimneys to greater affect as it improves the translation of the environment to reality in the players imagination. I'd also recommend the bushes, and well i'd recommend all the detail i've pointed out; the trims will have no particular negative affect on performance and i'd recommend the "junk" detail at "last" since it's the finalé, but of course junk props take a back seat in terms of priority against peformance. I believe you can get away with it though if you utilise sufficient horizontal hint brushes. The layout is well optimised keeping each CP location seperate.