The map may be simple but I think is better to have something simple balanced, than something complicated unbalanced
balance is the most important thing in melee
I think the main recipe for melee maps are 2 mercenary camps and 2 goblin markets, and 1/ 2 taverns
so I sugest a couple of mercenary camps (if you want balance lordaeron tile set mercenary camp) if you use the sunken ruin mercenary camp, it must be better defended since it has a powerfull unit (the matter is in discuss actually, many things are discussed)
in violet I marked the areas where maybe put a couple of mercenary camps
about the design, much water is tricky because it looks flat and empty, so a rule is if you put much water = a lot of work in tile variation and doodad (use fishes, plants, rocks, what ever) is necesary
your other map and this one have the same thing the water
I had the same problem in one of my maps (The Kraken if you are interested to see what I did) , to much water so I had to work it a lot, put tons of doodads so it would look alive.
study others melee maps is a good way to learn unique tricks
see ya