I have some but not used them much. I'm waiting for rounded pieces (like quarter circles, half circles). And I agree that there should be more single tile/2x1 tiled decor like chairs, tables, pilars, altars, statues, fauntains, dead bodies (to mark where enemies/players are down) and even pieces of standard equipment like weapons since a lot of times both PCs and NPCs like to switch their weapons mid combat an end up dropping their current weapon for the free action. And I'd also like some nature themed pieces like trees of various sizes, heavy overgrowth, light overgrowth, low rock walls, bramble fields, etc. but assume that will probably be its own themed pack later on.
As it stands now (I don't have any of the latest set, just the first two) many of those pieces are "built-in" on the largeer 10x4 and such pieces.
So I don't really use the pieces to form a whole dungeon out of. Usually I will just grab a couple pieces and make the room a combat is occuring in if I think of it. Or I just use my dry-erase board I have.