One owner notes that the only major difference between this crate and higher-end models is that the door locks could potentially be opened if a dog pushes the lever with their tongue. And indeed, several owners have noted that the locks weren’t able to keep their Houdini hounds in check. However, one individual notes that you could simply zip tie or caribeaner the lock if escape is an issue.
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.)