After reading numerous reviews on various cat trees, we settled on this one.  It is solidly made with plywood, instead of press board.  I could not tell from the picture if the top 3 platforms were flat or had an edges.  They have an edge, which I was happy to find.  It has taken several weeks for our cats to regularly use it.  Our 5 yr old cat has finally decided to try the top 3 platforms. I put a kitty warmer in the lower house to encourage them to use it.  That worked.  I also placed a blanket in the top house to make is softer.  That worked too.  As others mentioned, it does shake a little when the cats jump on it.  That scared them at first but they seem to have gotten used to it.  If there was no shaking, I would give it 5 stars.  All in all, this is a good product.