I purchased the 8' circle rug. We had a lamp and 2 chairs sitting on the corners. For some reason, it caused the other areas of the rug to always have a wave. ie it would not stay flat. It continued to have waves around the edges even after 2 months. To note, this rug was sitting on office carpet. The rug is currently on hard wood and we do not seem to be having the issue. 

Pros: Simple, affordable rug
Cons: Does not lay flat on carpet.