Large wood pieces with colored stem plants stimulate tree well, and smaller wood pieces add texture and detail. The open sky contrasts well with the densely planted lower half of the tank and allows the sense of depth to stretch towards the horizon line.
The interesting part of this aquascape is that Marimo Moss balls are broken up and planted on hardscape. They give a very fine texture look, which works well in this setup in contrast with other mosses and small plants. The downside of using marimo moss (which is actually a form of cladophora algae) is that they spread easily across the tank in time.