Friends of ours have Rico Rock stone steps and waterfall feature with a grotto. From what they said it comes in precast pieces and then assembled like a puzzle on site with concrete. I believe he said it was also tinted on site as well. It looks very nice, and pretty natural in how they used it.
They have had two issues with it. First, it is slippery when wet. Their son had a few stitches to show for it. Obviously, if the application is strictly ornamental, it's no issue. Second, there was no consideration made to the area of rock that the waterfall flows over and there is noticeable efflorescence staining. I don't know if that's the nature of the product or a result of a substandard installation.
As I said, it does look very nice, and I'm guessing that both issues they have with it could have been mitigated with a more conscientious install.
Another option you may want to at least consider is poured (actually, shot) in place concrete. This is the route we are going. I don't know how it compares in cost to the RR, but the biggest advantage is the flexibility of being totally custom to your build, as well as things like lights, planters, and even speakers can be embedded in the 'rock'.
Attached is the freshly poured (2 days ago) steps that will lead up to the top of our waterfall and access the slide. It's still very rough as another final finishing layer w/ anti-slip on steps, sculpting and color still needs to be done. The stairway walls will look a lot better after the final stage, but you can kind of get the idea.