My cat is loving this furniture, even the IQ box which I was a little skeptical of at first.  I found it very easy to put together.  The base and step design make it very stable.  The only complaint I have is the position of the toy on the top step.  It's practically in the middle of the stair which made my cat have to squeeze around it to lay down.  I removed it so he has the full stair to stretch out on.

Pros: Great value, easy assembly, sturdy construction