I would maybe add a whirpool in the lower corner with a girl in it. Nude girls please :)
I think the floor tiles are ok, perhaps puddles of water and shine is all it needs. What really needs help is the wall blocks that are waaaaaay too big, break each one into four. The showerheads are also too big and fat, they are 5px across, reduce to 2 px. Same goes for the hooks try 1px thick. The drain is also too big, its like a manhole. The door is 4 pixels too short.

Iso work requires a light source. You currently don't have one. The joint uses a top left left to bottom right.