Very nice project Simon! I really like the interesting shapes and layouts you've got for some of the larger ones. They do look very plain, but offering a completely bare/unpopulated version will make them much more useful and versatile, for those who don't mind taking the time to add their own elements.

I like the texture you've chosen for the floor.

My only suggestions would be to maybe try a less "busy" texture for the walls. And I think a bevel effect on the walls would also make them look a lot better. As they are right now, they look a bit flat. A bevel effect would give them some height and depth, making them look a bit more...wall-like.

Good job so far!