You might consider drawing trunks under the forest canopy, to make it more isometric than top-down, but otherwise the mountains and forests and your sketches look pretty good. The river could maybe do with some more hand-drawn line art to match the rest of it, but for its own part it's not bad... just doesn't quite fit in as is. If you really want to get picky about style matching all of the elements of the map, the line art on the mountains looks a bit more faded than the rest, but I don't know if I'd make that darker or the other stuff lighter. Depends on what you want to do with it. I do like the mountains the best... and that really big tree. Are you planning to do more with it?