It's not bad.
A few things, though:
The top house looks too narrow. Have you tried it with a height of 3 roof tiles?
The windows of the houses are oddly placed.
The pavement looks weird. There need to be more objects placed on the pavement or something, because as it is it just jumps out and clashes with everything else.
The back of the houses look strange. I don't know what it is, but the immediate use of trees and tall grass behind a house looks bad to me.
I also suggest that you either move the third house on the bottom up to align with the other two, or make the pavement 2 tiles deep instead of 1, just to see how it looks.