Yes, I agree that the right side is a little barren. I setup up the rocks etc, before the plants. Once the plants went in I thought that side needed something but there's no soil over there. The top of that rock has actually started growing moss all on its own as well as the wood. I once used those bits in a tank with moss but the moss long died off. It seems to have been revived which is nice.
I did have a dwarf puffer in there for about 3 months. He only ate snails and refused any other food I put in. He eventually passed on once I ran out of snails to give him having refused every other type of food in the LFS.
I have added no ferts yet. The soil should eventually deplete but I haven't seen any signs of it yet. I will probably use TPN+ when the time comes.
I will probably move my colony of lamp eyes and cherry shrimp over from the high tech before tearing it down to build another low tech. I'm getting into this now. I want to see more peoples low tech efforts. I am really pleased this is working out so well because having gone the high tech route with pressurized co2 I have found that it doesn't quite suit my lifestyle I am too busy to give it the time it needs and It becomes a little disappointing.