Well... the first three pictures are pretty useless. Might just want to make a camera in the World editor, set it to where you want and take a screenshot of everything. It also makes the scenery more attractive that way.
And the bottom part of the waterfall is weird, maybe because the waterfall doesn't seem "limited". It looks like it should spill out in every direction at once, but it simply follows a simple path. Maybe add a few rocks or something.
Are you using this for a map? Just asking, if so, what map? | 
