I've written a similar review on another version of this product, but just want to reiterate everything here.
I've knocked off one star because I think it's overpriced, but would spend the money again for the peace of mind this has brought me. I don't have a cat flap so bought one of these so I knew my cat had somewhere safe, dry and warm to sleep. It has taken over a year for her to get really used to it, but she now chooses to sleep in it during the day instead of coming inside, even when she knows I'm home. I once had problems with water getting in and found the liner damp and mouldy. Since washing and drying it thoroughly I have left the KatKabin outside through the whole of a Scottish winter, through wind, rain and snow, and it is dry. I think that it got wet during particularly torrential rain in the summer, when there was flash flooding nearby and cars were floating down the street. I don't know why other people have had problems with water getting in. I do also have it tucked right next to the building to avoid the worst of the weather, but there isn't much of a roof overhang.
Cats will find somewhere to shelter if they need to, and it takes them some time to trust a new thing. I worked quite hard to get her to trust it, and realise it was somewhere safe (and learn to use the flap), but it has paid off. I now know that even if I can't trust the Scottish weather, she will have somewhere warm and dry until I get home (except in a flash flood, but then I expect her to climb the nearest tree).