Hi Brian,
I like this picture quite a bit. That said, I have a few comments.
The eye tends to be attracted to the lightest values in a picture. In this case, that is the small patch of sky at the very top and the very light brown around and on the rocks. Thus, the picture as presented is really about the pool and two big rocks in the foreground with the waterfall becoming a less significant background element. If this was you intention, then you succeeded. I would crop out that bit of sky as it only distracts and I don't think you lose anything significant in terms of the tree if you do so. The picture has a very Japanese/Zen vibe to it with the rocks as the primary subject.
You might also consider making two pictures out of this. If you crop right at the base of the lower falls, then it becomes entirely about the falls and, I think, a good picture. Likewise, if you crop just down from the top of the lower falls, it further emphasizes the 'rock garden' aspect and makes for a stronger composition.
As a general comment, most people tend to leave too much stuff in this shots, myself included! What I try to do is look at each picture and determine what it's really about and then ruthlessly prune everything else away. In the case of your shot, it's about two different things, the falls and the rock garden, both are good shots, but they should be presented one at a time.