
This is weird... I mean, why not just put a resupply cabinet here? This is in Blu's spawn, after all.
EDIT: I just saw this post:
Don't worry about that. Having ammo there won't give Blu too much of an advantage, in fact not having ammo in that section for Blu will cause Blu players to run out of ammo more frequently, and give Red players an advantage as they have their spawn right there with a resupply cabinet and constant supply of ammo. This will especially impact heavies, pyros, demos, engies, and spies, who chew through ammo/metal/cloak quickly and rely on a decent supply of ammo/metal/cloak to stay in the fight. Perhaps a better solution would just be to move each team's spawn rooms further away from each other.

This is a very long spawn room.

Perhaps extend your spawn room trigger to fill the hallways, it's not clear that this is where it ends. I know there's a door there, but the door never closes after it opens. Is that supposed to happen?

This is what I see right after stepping outside of Blu's spawn. A wide open area, perfect for snipers and absolutely no other class. And Red's spawn is right in front of Blu's spawn. Red team has close by access to infinite ammo (perfect for engies, bad for everyone on Blu), while Blu has to walk back and forth through a long winding hallway to get ammo. Snipers + spawncamping do not make for a fun map. At least soldiers can't get a height advantage over Blu players exiting spawn...

...Oh, they can.
Perhaps clip off the roof of Red's spawn, or add something to allow non-soldier classes to get up here.

At least Red's spawn looks pretty.

You've got some overlapping textures here.

L O N G S M A L L H A L L W A Y S. Your map is full of them, they are LONG, they are SMALL, and they are UNAVOIDABLE. In fact, your map seems to suffer from room-hallway-room syndrome. This is bad level design. Small hallways act as a chokepoint, bunching players together and making them more susceptible to splash damage.

This roof on both point A and B gives soldiers an unfair advantage, perhaps clip it off. Also, that platform that the control point is on is awfully thin. Perhaps make it wider, otherwise Red soldiers up on this roof can simply push Blu players off when they try to cap.

Also, the underside of the cap point base prop model is see-through, which looks weird when looking under it.

The platforms for all 3 control points are pretty high up. Even without the aforementioned roof, Red has a powerful height advantage over Blu attackers, and once Blu pushes up onto this platform, Red players on the ground will have a hard time stopping Blu from capturing the point. Also, the drop is definitely greater than 256 HU, and any drop from above 256 HU will cause fall damage, so 256 HU drops should be used sparingly. That's not to say that they should never be used- some maps make good use of them, such as Badwater- but you should consider how they will impact gameplay.

These doors are broken. After exiting, you can't re-enter, as the trigger areas for these two doors are reversed.

Perhaps adjust this Blu respawn room visualizer so the textures don't overlap so much.
EDIT: Another thing I noticed while playtesting with bots (because I'm bored):

You can stand above Blu spawn. Talk about overpowered. I think you have absolutely no concerns when it comes to Blu having too much of an advantage with a resupply locker there; Red is already incredibly overpowered.
Don't get discouraged. Despite all of this criticism, you are improving. See this:

Your first map was the equivalent of the beginner map with elements of intermediate. And that's not a bad thing, we've all been there. This map is the equivalent of the intermediate map. Keep working and eventually you'll get to advanced and even expert. Study up on Valve maps. Figure out which ones are good and which ones aren't, what works in those maps and what doesn't. Figure out why Dustbowl is a bad map and avoid those things. Figure out why Badwater is a good map and try to apply those principles to your map. And although it may seem like you have a long and hard road in front of you, remember this quote:
"The journey of a thousand miles begins with a single step."
-Some famous p̶h̶l p̶h̶i̶l̶s̶o̶p̶h p̶h̶i̶l̶o̶s̶o̶s̶o̶p̶h really smart guy