Most garden waterfalls, or at least those that we've built, are constructed with natural stone. Stacked flagstone or some other flat rock like that used in this small waterfall spillway is very easy to work with, form, and level for even flow.
There is a mysterious atmosphere with the way this is built and planted. With the actual source of the water being hidden and flowing out out from under the bush, the water feature appears more natural and a part of the surroundings.
Depending on the amount of flow, even a small waterfall like this can create a lot of sound in a small garden. It doesn't have to be big to add good effect to the surrounding landscaping. Several of these spillways would create a good volume of sounds which can sometimes be too much for some enclosed small gardens.