To improve the map, you´d need more detail.
But you can only have more detail if you size it down.
The way I see it, the basic gameplay is around sniping at each other from the fort tops.
I don´t think you´d neccesairily need so much of space (especially width) devoted to this.
So make it smaller, until the basic layout unlit is about max 1000 wqd.
For the design part, when you have some wqd headroom, add some pillars or tower-like stuff to the fort walls, using a diffrent texture. This might help break up the flatness of those walls, and make it look more like forts. The forts atm are just walls.
You might frame the waterfall with rocks, because it looks weird comming out of nowhere.
Maybe add a back wall of some sort to the fort´s upper area, it´s always weird if the sky is blocking you.
The water parts look like denaturalized canals. Don´t think those fit too good into medevial setting. get some corners into them to make some more natural rivers and streams.
This can all only be done if you reduce the size of course.
Consider adding some solid structure in the middle of the map. Watchtower or something. A block of solid in the middle might well occlude up to 25% of the map. Consider two of those.
You´d still have the snipe across the map thing, but at less wqd and more tactical possibilities too.
Light: a big map like this won´t really work with loads of small lights of course, but try NOT to get rid of every shadow. Choose a cloudy skymap, so it´s more believable that the lightning has shades.
Just try to find a balance with big lights, that still give the map some contrast, but don´t show that obvious star pattern you get from them.
Why does the bar have to be that big? looks like a disco that´s not yet done. You could make it smaller.
Remember smaller means also you don´t have so much to do when detailing it. Goes for the whole map.