Hi Daine,
There is often more to making a great photograph than just setting up the camera and pushing the button; often it is necessary to do some housekeeping about the location to remove distractions from the photograph.
In this photograph my eyes are distracted other 2 little leaves in the bottom of the frame and the dead branch located on the rocks in the upper right. If you place your finger over both these items you will see that without these distractions the picture does look a lot better.
If I were making this photograph I would be inclined to remove the two leaves before making the photo, and if the conditions were safe enough I would also wade into the river and pull the branch off the rocks. This might seem like a lot of work prior to making a photograph, but it is often easier than trying to Photoshop out the branch later on.
Regarding the leaves... as an alternative I would sometimes look at adding leaves to the photograph... spend ten minutes gathering leaves and throwing them loosely into the foreground and you might add the appearance of Autumn to this scene.
There are two other considerations I would offer with a photograph. The first is your decision to shoot vertical; the water flowing over the rocks has a very calming effect and I feel it lends itself more to horizontal image. I would be inclined to move 2 or 3 metres downstream and use a slightly longer lens so that you capture more of the front waterfall and make the back waterfall appear slightly larger in the frame too.
My other comment would be about the length of time that you have used this exposure. Three seconds almost makes this photograph appear to milky; I would keep your aperture at the same setting, but I would increase your ISO one stop (100 to 200 ISO), or perhaps use a less dense Neutral Density filter so that you can have a slightly faster shutter speed. I think one or two second exposure would produce a more realistic result.
Cheers, Anthony.