It being your first map doesn't mean that you shouldn't try to improve upon it.
It isn't that bad of a map for a first, I'll give you that. It's semi-unique, plus I can see that you took some time with the scenery to make it look a little more decent.
Try to make a couple slightly bigger and broader islands, while having some little islands like you have now still scattered about. So far, most of the islands don't look too inviting. They're all a bit small.
I like your ideas so far, and the fact that you've experimented like this (evidence of thus with your ctf_harbor). Good luck.
Edit:
Well...I forgot about your surprises. I just downloaded the map.