I purchased the 42 inch crate as a recovery area for my elderly cat. She loves it and continues to use it as her private apartment even though she is currently well. She won't use the shared food or litter boxes anymore and she will ask to go back in her crate (by rattling the door) when she wants either. She spends the night there and I've never had to coax her in, only out! If I had known she would love it this much I would have gotten the 48 inch size.
The wire is thinner than my old crate, which is also made of the black metal, but it is still sturdy. I used to have the really heavy silver steel crates but they are ugly and stronger than necessary. I guess if you have a dog you think might get out, you should use zip-ties all around and bungee the door when the dog is inside. The ... full review
Update: We traveled quite a bit this holiday season and this portable crate was absolutely awesome! I have seen some reviews about bad zippers but suspect it's due to misuse. You have to raise each side before zipping it -- just common sense, people. Otherwise, there is too much pressure on the zipper. I think zippers on this crate are sturdy. Another suggestion is placing your dog's favorite bed inside. The crate (we have extra large) has plenty of room to add an extra large fluffy dog bed our dog loves. Because the crate folds flat, we place the crate in the cargo area and cover it with dog's bed when on the road. The dog sprawls like a queen! :) When we get to the destination, we unfold the crate, throw the bed inside, and voila -- cozy house that ... full review