I'd shrink the outside area by 1-2 tiles on each side. I don't mind having it be completely open out there but I think the corners are a bit far and only players on the very edge would be able to see someone sitting out there. I think 3 tiles on the outsides is enough for recons to move around. That being said I do think it is really interesting how you have the entrances set up on the left side, two pretty close together but a tight path between them on the outside. I think this is an area that would benefit from being 1 or 2 smaller.
As for the interior, I'd really like if you added some elevation inside. It wouldn't have to be much, and it should definitely be grenadeable but I think having a bit more of a reward for taking control of the middle is appropriate. The way I envision it right now is one team will get a squad of 4 or 5 group up together eventually (at least thats the goal) and I think if you inevitably get to that point you should have some sort of positioning advantage. While being away from the spawns and having the walls is great, without much movement options I feel that it wouldn't be too hard for one or two good players to walk through that when I think it should require a coordinated effort to break that up.