It was very interesting to me to see the backlash in the US when PDE was first aired in the UK. The US dog magazines were furious, proclaimed the documentary "sensationalist", and accused Jemima Harrison (the doc's producer) of collusion with the animal rights bogeymen in an ongoing campaign to rid the earth of purebred dogs. Remember, at that point, the program wasn't available on YouTube, hadn't been aired in Canada, and hadn't been seen by the (very vast) majority of American fanciers.
Naturally, I was very eager to watch it when it became available online, and the first thing that struck me was Harrison's obvious love for, and appreciation of, purebred dogs. This attitude may be peculiar to the UK (in the US it's not very politic to sing the praises of purebreds), but the tone was plain to me: these are wonderful, beloved breeds, and they have (through whatever mechanisms) become beset by genetic disease and structural unsoundness, and something ought to be done.
It doesn't take an expert to look at a ring full of modern Bulldogs and think, "That doesn't look right." The dogs snort, wheeze, and gasp as they move around the ring. Ditto the sad-looking modern German Shepherd, who walks on his hocks and seems to slink around the ring. A little layman's probing will reveal that Bulldogs, Pugs, and a number of other breeds in their modern incarnations cannot even mate naturally, much less give birth without a C-section - it's physically impossible for them to conceive without human intervention. I think it's fair to say, with all due respect to those breeders who have devoted their lives to these breeds, that exaggeration and extreme forms have been created that are detrimental to the dogs themselves.
This is without even touching upon the preponderance of genetic disease in certain breeds. Many breeders do work hard to reduce the incidence of these diseases, but I think it is all too tempting for many to simply take their chances and breed to that gorgeous, Best-in-Show stud dog who's a carrier.
As an active participant in AKC conformation and as someone who has grown up "in dogs", I honestly do hope that PDE creates dialogue in the US - not just in the UK - about how it is that breed standards, judges, and breeders interact to create the dogs we see today. It's not about blaming anyone, it's about honestly evaluating where we are now and making wise decisions about how we are to move ahead to create dogs that are sound, healthy, and happy companions. At the moment, unfortunately, the American fancy seems to want to keep its fingers firmly in its ears.