I actually bought three of these and love them all.   Zip off top was needed to keep my dog (Maltese) from climbing up and out, but he is older and I use without the top zippered on.  He stays inside and is very comfortable.  I do have to clip the zipper pulls together on the door as he can open the zipper.  I keep one at my parents place so there is a pen for my dog when we visit.  Easy to pack up and move if needed and very easy to clean (use outdoor hose and soap, then air dry in the sun).  Can spot clean very easily.