very nice catch, first things first, i have to say that i am pained when viewing this image, not because it is bad, but it is too large for web viewing pleasure on my laptop.
please post up slightly smaller next time 800 longest edge is usually good for horizontals, and 650-700 good for verts.
1) the focus seems a tad off - what sort of settings are you using? it is either that or diffraction (plus crop), or handshake. the rock SHOULD look sharper than that, and would look better sharper too.
provide a sense of "grounding" amidst the torrentous motion around it.
2) exposure of picture is a tad under, but this is easily corrected by processing.
3) work to make the "splash" stand out amidst the torrents, also try cloning out the rock on the bottom left, not that hard when it comes to blurred water
here i did some quick work on it, let me know if you want me to take it down. basically highlights and shadows were the most important step here, everything else is just minor tweaks