I just recieved it so haven't quite gotten enough time to give full rating.  It was easy to put together and seems tough enough for a 9 month old kitten.  He hasn't used it yet (at least I haven't seen him go in to use) but he was comfortable climbing in and out prior being filled with litter.  It's now in place and we'll see if he's comfortable using it.  For now I'll give 4 stars just because it was easy to put together, sturdy enough (so far) and he did go in and out with ease even before setting it up completely.