I just ran through your map and it is looking good.
The layout is very promising. There is sufficient space to maneuver in most places and a multitude of routes to and about the point. You have some very tight choke-points leading to the point-area from the ground level but, I suspect those to be intentional. I think that those choke-points will serve gameplay well because it would give defenders on the point an advantage and force the attackers to take the long route to gain a height advantage.
You might want to put some player clips over the point to smooth out running over it.
I like the towers, but they might be a tad detached from the action. Perhaps, this is a good thing. They are certainly sniper and engineer friendly.
My main concern with the layout would be the proximity of the spawn to the point. It might be too easy to run back to spawn for health or too tempting to push into the choke-points and camp that exit. Also, it might be difficult to keep a teleporter up. You probably would need some playtesting to be sure about all this though; I'm just trying to predict some potential problems.
The visual theme is coming along; especially for an alpha. A few things though: I must disagree with your choice of textures for the spawn rooms. In my opinion, those textures only really fit with flooded rooms in rainy maps like in Sawmill. Also, these are probably place holders but, the ramps out of your spawn are textured with a vibrant wall texture that looks out of place.
On what Tob is talking about. The platform appears to be perfectly supported by some wire right underneath it. It's not exactly structurally sound but, I don't think I would have even noticed it because of how familiar I am to Lumberyard's point.
I hope that helps. Your map definitely looks promising. I wish you good luck on developing it further.
P.S. The name "Heist" has already been used. I have a ctf_heist I downloaded awhile ago in my map folder.
