I coveted after these for awhile, and finally got my hands on some. They are my favorite "hidey houses" for our rats and guinea pigs. Not only do they love them, but so do I!
They are so easy to clean, and keep the bedding underneath cleaner as well, since they do have a "bottom". The two pieces snap together mostly easily (once you get the hang of it). It's a snap to take apart and clean (fits in the dishwasher, even!), and nothing has ever stuck to it that a rinse with water didn't easily remove.
The one thing I don't like is despite the apparently quality of the plastic, the rats did chew some bigger "air holes" in the sides. But since it's not a huge deal (as rats WILL chew!), I didn't take too much off my ratings.
All in all, it's my favorite hidey house for all small animals. Can't beat the price (cheaper than other "igloos"), and it's a quality product that will enhance any cage.