This map was a great play, and I've got to say that it's probably one of my favorite KotH maps now.
The strange thing about the map's design is that even though it's quite open, with its objective in the center and the battlements around the edges, you've made snipers work. I tip my hat to you for this. On no other map have I so many times been helped by a cowardly jar-man staying behind while I charge into the fray. It's an amazing feeling, charging in with your flamethrower when you have half health, coming up against a heavy and fully expecting to die, only to have the well insulated behemoth slain, not from behind, but from afar, by your van-dwelling teammate. Truly, I feel that this is how Snipers should work with a team, and it's an amazing experience.
Don't make it less open. (Says the Sniper-phobic corner-hugging Pyro.)
One thing that really bothers me (aside from the spies' backstabbing, sentry sapping ways), though, is that some of the railings around the outer perimeter are unbreakable, while most of them can be broken. If only for consistancy's sake, I'd suggest that all of the railings along the outside of the tower be made breakable. (I was calling for this during the gameday test.)
Another thing pointed out during gameday is that though the wooden textures look great and fitting for a construction site, they camouflage red sticky bombs better than blue ones. In light of this, I believe that I suggested earlier to change the wood texture, at least on the 'hill' to a very light or very dark metal. Alternatively, might I propose a lighter wood texture? Some of the very light woods don't hide BLU any more than RED.
During my time as an engineer on the map, I was hard pressed to build things not only because of the openness of map, but even moreso because of a couple of spies who kept breaking everything (ahem), and more notably, a lack of metal aside from inside spawn. Health was similarly scarce, but I didn't find this to be as much of an issue issue, perhaps because of my kamikaze tendencies that I've developed playing combat Medic and Pyro that have me making frequent one-way trips to the spawn room.
In any case, I'm surprised that there's not more feedback here. This is a great map!