The values and tonal composition doesn’t read that well because the trees are pretty close in value to the cliff. Adding lighting information to the trees would help.
The waterfall itself can use some tweaking in terms of the way the water falls. Gravity is pretty consistent, so the water will fall in a uniform trajectory. If there are rocks that protrude out from the cliff and causing the water to change it’s trajectory, you need to show it clearly.
I agree with the inconsistent look of micro-detail in the trees and very vague brushwork in the background (which is actually your main focus).
The overall composition with those trees feels a little unnatural. Maybe move the right one lower and much closer to the camera.