It's nice though I have some suggestions (was actaully wondering who made that map, looks like I found you

) if you have the time or the motivation to continue with the map, it might turn out good.
Like that there's another way of getting into the enemies base through the water. Though, I haven't tested it with other people so I don't know how the spawnpoints are, but I suggest (if it isn't fixed) that move some spawnpoints out of the base. Otherwise capturing the flag is close to impossible, unless there are few people.
Another thing is I would like that there would be a weapon in the towers, nex, rocketlauncher or mortar would do good, maybe move the machinegun from that hill to that tower and put some other weapon on the hill. These needs to be strategic placed to actually do any good.
Another cool suggestion that is just that

is that having another way in the base would be good. Like from the left side of the wall where the flag is. Imagine this, where to furthest teleporter from the base is, there is a alley or something into the wall which leads into the base. Two ways out, two ways in.