Several owners complained that their dog was able to bend the wires and escape, so this isn’t a good choice for dogs who are escape artists, although it should serve fine for most pooches. Additionally, a few owners reported that while the crate can be collapsed, it’s not especially easy to do, so it isn’t a great choice for owners who plan to travel with the crate frequently.
Addendum added January 28, 2013: My vet had never noticed these carriers because I had never put one up on the exam table until my last vet visit. She looked at it with interest and totally concurred with my opinion of having a small, but open carrier for my two (panicky) cats. She has seen more than a few overheated pets in too enclosed carriers. Since I live far from the vet I always carry spare towels for the bottoms of the carriers and she found that the "stable floor covering'* I use was an additional comfort feature for my pets long trip to their appointments. (I just ordered the larger size of this carrier for my "Phat Kat" and will donate her previous carrier to our local animal shelter.)