"Read some tutorials, look at the good and bad of maps that others have made, including Valve officials, and try again, but this time have objective eyes look at your work-in-progress and tell you what's wrong and what could be improved, and listen to them." key statement "and listen to them."
I stated what's wrong with the map, I stated it in a dry tone, but those are the basic technical errors. I'll go through each and every point if you want, but if you're not going to listen I'm not gonna waste my time. Sorry for the cynical point of view but I've seen a lot of people say "give me feedback" then leave the Snarkpit for a place where people will tell them their map is leet. Feedback is a two-way street, there's no reward for the critiquer if the critiquee doesn't listen, which is part of why the Snarkpit has lost it's "umph." Sorry for ranting about the SP's past, but there was a day when a mapper would have his map torn to shreds and spit out in dry chunks of criticism and be grateful someone with more experience took the time to help them. There's no more humility in saying "give me feedback."
There's a wealth of knowledge in the collective noggins of the Snarkpit, but you have to be willing to accept the form it comes in, which is often links to tutorials or even the search page. Expect more honesty than kindness in critiques, I'll be kind right now though.
The brightness on your light_environment is too low, and it looks like you ran VIS and RAD on the "fast" setting, since the entire map is visible from any given point (fast VIS+skybox) and the lighting looks really sharp and ugly (fast RAD causes this).
The cubemap problem is on the very surface just the fact that you ran buildcubemaps in HDR mode only, so people running without HDR don't even see cubemap reflections, just purple-black checkerboard. The placement of env_cubemaps is fairly easy to learn if you don't get too much misinformation, but it's one of the harder things to master on Source, it basically boils down to trial and error and experimenting.
Now it gets into the debatable issue of prop_physics vs prop_physics_multiplayer with regard to CS gameplay mechanics. According to some, barrels are basically the new crate only barrels not only don't make sense they interfere with the game. Others believe physics objects add a new level of tactics to the game, scatter the cabinets on office and make it a little harder to move around in key spots, etc. But both camps generally agree, too many physics objects is a bad thing, especially when they're placed without much though as to how they'll affect gameplay. In most of the Valve official maps the physics objects are strategically placed to give an advantage, or 'temporary cover.' The basic prop_physics entity is also bad for gameplay because the collision has some really weird behavior like occasionally launching players into the air when they jump, as well as hurting players for no apparent reason.
The map just isn't finished, plain as that. It usually takes the input of at least two objective people to make a map great, but even just one person seriously critiquing you map will not only make the map better, but improve your mapping skill. Fixing bugs and exploits is also a hugely important part of finishing a map. For example I was able to get outside the basic level of cs_apoc, get on the beach displacement and basically everywhere else in the "non-play" area.
I'm not going to even go into CS layout theory, I've already spent a loooong time on this comment and it's out of the scope right now. In any case, CS:S is a very particular game in terms of mapping. It's also the least likely to get you recognized by anyone important. It's difficult because the game is so clearly defined in which map elements work, and there's no passing off a poor layout to people who know what makes the game fun. Basically single-player mapping is the most important in getting recognized, then DM, then CTF, and at the very bottom is CS. A lot of the skills are transferable, some you can't get anywhere but a few other places, but CS is fundementally different from most games at it's core, and the maps reflect that.
