C++ generation is small (only 4 files) with a good performance and logic easy to understand.
There are also files for loading screen (slate) and C++ finding Savegame files. So additional metadata file is not needed.
Rest things are in blueprints so it is so easy to modify like chaning voxel size, textures, effects, post process, sky, items etc.
UMG is also quite simple.
I will also provide the online documentation soon!