Great idea but poor roof design :-(
I was very worried when I bought this that my cats would not use it; they found the packaging it came in more exciting than the built thing. They soon came to like it, though they've never used the enclosed downstairs room.
The roof is good for water run off, but has not been strengthened with struts to keep the roof in shape. Over time the roof has collapsed (needs replacing!); it is splitting into separate layers and the underside is a mass of mould even though the roof felt is still intact.