I tried out your map and I managed to play it trough on hard difficulty. :)
The first thing I have to say is, there are ERROR models, due to most of them are Episode 2 models. Same goes for textures. That made me sad because for the first map, it's not bad. There was a few problems tho.
ERROR models and missing textures
Alot of props and stuff are from HalfLife2: Episode2. The problem is HalfLife2 doesn't have those things. I recommend to put this map in the Episode 2 category. Images: (-----)(-----)
Error messages in the console
I saw a huge list of error messages in the console, Most of them are saying that certain props doesn't have VPhysics. You can fix those easily, by going in the prop's properties (Double click on the prop) and change the Collisions from "Use VPhysics" to "Not Solid". They didn't make collision models for skybox models because the player never meant to touch those in the first place. Image: (-----)
I know, it's annoying because I had that problem too. You can fix it by placing an entity on your level called "shadow_contol" and change the "Shadow Color" to a greyish color like: "128 128 128" (Default) Image: (-----)
A few more stuff:
I found that annoying that the combine soldiers just rush you and there are not much cover for you, that made it pretty hard to complete your map on hard, because of that I died once. You added autosave points that was really pleasant because I forgot to save by myself. The ending was very lazy I must say, you interact with a locked door and it just throws you back to the menu. I also liked that you placed alot of prop physics because when a combine soldier lobbed a grenade in the middle of an office room it's just made a huge mess in the room. I would add a gravity gun for the player, to make use for the props scattered around the map. I noticed you used Nodraw texture witch is very great. Image: (-----) As I said this map is not bad for the first try, it has some faults but it can be fixed easily.
I'm not gonna give it a rating on Game banana, because I know you could do better, so I'm just gonna rate this here. I give it a 4/10 so far. Good luck fixing it, check out some tutorials on youtube and visit Valve Developer Community where you can find anything what you need.
Best of luck, ~Peredice
P.S: Please don't trash this map yet, I need my exemplary feedback