As obviously said before, the tree's need working on, im not really a great LAT, but i can try my best to help you improve from an artist perspective :P
Tree's are organic, and if you want it to appear as though it's by or in the middle of a forest, you dont want them all in a perfect line, overlapping each other. So maybe make the trees shapes using the tiles, and if you cant use tiles to create the edges, use the images and add them to the edges.
" Dont think i explained it too well
"
The houses are quite interesting, remind me of little hobbits for some reason, i would'nt put them in a line like that, move one a bit down, one a bit up, and so on.
It's pretty hard giving crits to a level thats not finished xD
Ill stop my post here until someone else posts, i dont want to drag on about my none-sense rubbish :P
::bunch the grass patch things together in areas:: Test.