I think the setup looks great!
The rocks look sperfect, but have you wet them? Rocks hide their true colors til they are wet. Maybe you should wet the lighter rocks, see what they actually look like?
Maybe mix the two colors??
Also, what type of wood is that? regular wood will decay a lot faster than DW.
Thanks for the feedback.
I have wet the rocks. The ones in there are charcoal black. They are actually the stuff they use on roads. The lighter colour ones I have tested too, they don't change under water. I don't like mixing rocks in a scape like this because it tends to make the design less attractive. If I was doing a rock riverbed I would. but then they would mainly be the same shape. I think one differing factor is enough.
The wood is the root off a willow (probably) It is light but will last long enough. What do you mean by driftwood? I mean what makes it driftwood and not regular wood?