At first glance it looks awesome. That is of course... only at first glance. There are so many little problems here I don't even know where to begin. However, most people don't pay very much attention to things so I'll just point out the things that immediately caught my eye in each image.
First Picture - Skipping this one since you took close ups.
Second Picture - The stairs are so damn long and thin. It just doesn't look right at all. If you were to thing 3-dimentionally those stairs wouldn't be stairs at all, and more like a ladder. Only, there is nothing to hold onto, so they would be unclimbable. Perhaps you could make it so the cliffs aren't so incredibly high.
Third Picture - The lower waterfalls. WTF? The hell were you thinking? Why do you have the part where the waterfall makes contact with standing water (the foamy part) right in the middle of the waterfall? That makes no sense!
Fourth Picture - That cave on the ledge. Or is that a ledge? Whatever it is supposed to be it doesn't work how it currently is.
Fifth Picture - Upper right corner. Does that grass from the lower level come up onto the cliff that is like a billion feet above it? Also the ramp or hill or whatever that connecting part with the pathish dirt on it is supposed to be doesn't look right. Try using the tiles meant for representing a ramp/hill/thing.
Sixth Picture - The only thing that really jumps out at me here is the ledge with the cave again. The wall doesn't meet the edge smoothly. It just looks weird.
There are so many more little things that are messed up I am not going to list them all. Not to mention the qualm I have with your tileset. Number one complaint, the shadows are all differnt colors, which looks totally rediculous when merged together, not to mention causes issues with transparency. You maps also seem possibly a bit TOO cluttered. Its all chaos and no logic. Sure, nature is rather random, but it is still governed by certain rules. You should try to make you map feel natural.
P.S.: Out of pure curiosity, how do you intend on making that middle bridge functional?