This map was easy enough to play. it wasn't too challenging, more or less it was easy and I quickly overwhelmed red players base, maybe you shouldn't have mad their base so huge, and left some defenders in it.
At first, I was almost overwhelmed until I established a good base, good income of resources, and had a sizable force to defend my base long enough until I had enough money to invest in siege weapons. The red team was at a medium, he wasn't too weak or too tough which was good, in the beginning when you capture the town center you should be given some sort small force to defend your town while you build up and collect resources. All in all its was an ok balance.
I didn't see much eye candy, just some basic things such as city streets, rows of houses, a giant wall that stretched from one end to the other end of the map. I think you could have gone in and selected some different terrain instead of using a solid carolina grass. Look through some of the eye candy thread, and eye candy guild web pages for some ideas, thats where I got mine.
Map Design: 2
I think you need to add some variation to your map. You had a huge forest, maybe you could of added hills or cliffs, maybe a trade route flowing into the british city/fort, and to the spanish base. Some thing to spoof it up a bit.
I thought the story line was pretty good actually. I liked the idea that you had a reserve of spanish that you could go send at anytime, the idea of the british explorer running away as you approached like an ambush. The instructions were pretty basic though, just destroy the british base. You should add more secondary objectives like maybe capture a small british base and free some spanish soldiers held captive there.
Additional Comments: Good job anyway, you have great ideas but you just need to buff them up, ask around in the forums for help and opinions, say your not good with triggers or cinematics, which are a little hard for me, maybe someone would help you with that. I think a good cinematic would do wonders on this scenario, one int he beginning and one aat the end.