The main disadvantages that I can name at the moment are:
— Repairs, etc. are time consuming
— Cables etc. cannot be laid on top of the floor slab
— Space heating is even more sluggish.
Perhaps one advantage is that underfloor heating in the floor slab is somewhat cheaper? In Scandinavia, this method is considered quite popular, also because of the lower residual moisture because there is no screed. But otherwise, does anyone know of any distinct advantages? Or even have any practical experience with it?