Well at first glance, it looks very good. But, as always, on closer inspection, you can easily see a few key faults. One, what's up with the water? No rocks? No deep water? No sand at the base of the mountains? If you're going to use that much water so that it dominates the map, try to fill it with something. Yes, the player won't see most of it in-game but at least try to add some a few touches here and there to make the experience a little more visually stimulating. Merely adding a layer of sand that encompasses the mountains on the bottom tier would make it look MUCH better.
Besides the water, there are also several other locations throughout the map that look empty. You used a lot of flowers but they just don't seem to fill the space that well. Maybe if you varied the vegetation so that it wasn't just the same flower over and over again, it might look a little better. Perhaps using some of those rocks not exclusively on the mountain? Or maybe a bush tile? Your choice. Other than that, the tile selections are pretty good. I noticed a tile error by the northeastern house where you thought you could bypass the two-layer rule Another thing I noticed, which might not be a tile error but is more of a personal preference, is the lack of shadows underneath the bridge tiles. It will make it look a lot better in my opinion (and not to mention more realistic).
Other assorted things: path usage is decent. You could probably get away with a little more to cover those bare spots. Still I like the way you made it seem as though the path was dribbling over onto the next mountain layer. However, if you're going to do that, why not put down some path on the layer below? I know that's not a very good description but hopefully you get what I mean Uh, what else... The mountains are fairly well shaped, save for a handful of spots where you made the mountains like ONE TILE too long, therefore causing it to appear a little too straight for my tastes. But on the whole, it's very good. Tree placement is good although I'm not too keen on the diagonal method. Still, if it works for you, I suppose it's okay. You could probably get away with a few more of the small trees here and there. I don't like the way that the player only has one tile of moving space when trying to enter the house on the island. Grass placement is just fabulous! I've got nothing to complain about there
So yeah, that's pretty much it. Overall, it's a great map but, as with most maps, there's always room for improvement. Keep up the good work!