I like the 2 scratch posts on either side .  the cats can scratch at it from many different positions. The material is super soft and they like to both sleep/hide in it as well as chase each other running through the tunnel.  I also like how easy it is to store.
The only thing I don't like about it is when they tumble around, if they jump right in the middle it one of the sides will flip up and fall on top of them and they are heavy.  So I have to monitor them around it so they don't get hurt if they jump on top of the material part