Installed!
Installation wasn't as hard as I thought it was. Although technically you don't need any additional tools aside from what is provided by Oneplus, it was much easier to use my own plastic case removal tools.
Back appears to be a layer of bamboo veneer laminated onto the plastic back. The veneer itself feels excellent and smooth, though there are some imperfections in the actual grain of the bamboo itself. That is to be expected from a product like this.
The added thickness of the bamboo raises the case above the bottom of what would normally be a protruding camera. The 1+ logo itself is painted on and I do not know how durable it would be long term. Color of the plastic back mostly blends well, though there are some places it doesn't feel quite right with the bamboo colour. Overall a nice quality product... though the bamboo one will be hard to come by. White is available in quantity and is reasonably priced.