The water looks good, but the other stuff doesn't look quite as nice.

I kind of like these although I have a few things that urke me.
First thing being that the rocks should possibly be in the ground.
They just look like they're ... "there", sort of floating or somthing.
Next being that everything has a black outline, I can tell your spriting skill by your submission.
As far as constructive criticism goes, I'd suggest reading a few tutorials on spriting. These tutorials were brought up in "Devolopers Exchange" in the forums.
The water is great, looks like a Final Fantasy tile rip to me but never the less great.
To squareish honestly.
These aren't excellent or great but are good and I say this because of the detail some tiles lack.
Remember, always show others your sprites and tiles in Devolopers Exchange on the forums before submitting. There you can have others review and critique your work, for the best.