This is quite a compelling mapgen - with a little fine-tuning you can get islands that look reminiscent of Hawaiian landmasses!
This mod adds its own trees and flora - so it is not compatible with mods that add flora or new biomes yet. You can enable them - they just won't show up in the mapgen with this mod enabled. Support for customized flora/biomes on these islands would be great!
Additionally, rivers are not a thing in this mapgen, sadly. There are 'inlets' of water and reservoirs which spawn inside islands - sometimes this can result in a huge chasm in the island all the way down to a muddy puddle! (which seems to not be intended)
So, there is a bit more work to do here, but this has the beginnings of a masterpiece! Kudos to Termos.