Just looking at the screenshots alone, I am worried a few of the paths might be a bit too narrow (especially in middle, where most of the action of the map will occur). With the lack of a third side-route and the general straightness of each hallway, Snipers are going to be quite powerful in mid. One player can guard both chokes coming out of mid, making it an overpowered Sentry/Demoman position. If you added, say, an underground side-route that connected to mid for both sides, it would be a lot more viable for Spies/Pyros/Scout to play on this map. Otherwise, I don't see myself, as a Spy, being able to get passed what would surely be a spam-fest in mid.
Also, I can't tell - where are the spawns? I'm guessing they haven't been put in yet. For the future, it's absolutely vital that you make sure that the path to and from the flag does not go pass the enemy spawn. If it does, your map will stalemate for an eternity.
For a good, indoor CTF layout, take a look at pro_turbine. Just don't copy its boring aesthetics.
Hope that helps!