As someone who has purchased WTB from McMurray and is now looking to other avenues to create colored eggs I have many opinions as to why I would not purchase hatchery WTB again, though I can't say that my personal experience, which is limited to only two of this breed, a hen and rooster, has anything to do with why others have chosen not to pursue the breed. In creating my flock "wish list" WTB met all of my greatest criteria: strong free range capability and high production, plus the fun factor of getting blue eggs. I felt that this made a WTB the perfect roo for my flock because I could create my own colored layers by crossing him on brown layers, as well as create more WTB with my hen. From what I have heard, roosters are a complete trial and error thing either way, but mine finally had to go because he failed in every capacity. He was human aggressive, failed to alert the flock of danger or usher them to safety when aerial predators were present, he was not "sweet" to the girls, fertility was spotty, and finally, as his first offspring have started to lay, I can confirm that he is not homozygous for the blue egg gene. 
As for my hen, we absolutely adore her, but her eggs are... problematic. For one, she lays incredibly weak shelled eggs, which I do acknowledge that issues can be more prevalent in production breeds. Sometimes they will be broken in the box if another hen has laid after her and sat on the egg. None of my other chickens have this issue and I have tried various feeds with supplementation. Additionally, she lays a large, white egg rather than a blue. As for free ranging she is a rockstar and is incredibly entertaining in the way that she will chase and harass my dog, who thinks that they are best friends playing chase. 
I haven't completely sworn off the breed and have been looking at some breeders to potentially order hatching eggs from, as I would trust that they are more likely to have consistent genetics. I would also like to add that Mcmurray was great when I reached out about the white egg and refunded the purchase cost of these two birds. I tend to think that a hobby breeder might be the way to go if you're interested in getting birds that may be less likely to have genetic surprises!