Although they were developed (and some directed) by Moore and Dinner, who seem to have some artistic control, and the US and UK production staff also seem to be consistent (to maintain the look?), they're all different. Since the writers change every episode I wouldn't expect more than half to really be "faithful" to Dick. I'm not sure he'd appreciate fidelity, but I agree the writing could be better (I like that it's not consistently _Dark_ like a _Mirror_ clone). Maybe I'm jist not a DickHead, but I didn't find all of his original shorts great (or necessarily original).
Fidelity to the plot isn't paramount, but I'd want fidelity to the essence of the story. Both were violated in the aforementioned episodes.
It's worth pointing out that Dick's stories are dark. Autofac has one of the most apocalyptically pessimistic endings ever written (though his seminal "Second Variety" manages to be even darker). I can't think of many that are in some way uplifting. Most of his best stories — "I Hope I Shall Arrive Soon", "Impostor", "The Electric Ant", "A Little Something for Us Tempunauts", "Second Variety", "Explorers We" and "Colony", to name a few — are end on a dark, often depressing note. Of the few classics that aren't, such as "Paycheck" and "We Can Remember It For You Wholesale", would probably not lend themselves to Black Mirror-style stories, although I'd love to see faithful adaptations of these. (By the way, if you don't find these stories great or original, I don't know what to tell you. They are masterpieces!)
If the producers didn't want dark stories, it's strange that they would choose Philip K. Dick.
I guess that's what I'm saying. You may not like any of the adaptations (BladeRunner, MinorityReport, TotalRecall, or the HighCastle series), because none are faithful and most only tangentially cover the idea... but they've almost universally been successful. I think that's why they chose him (and I think some love his work) even if they're not at all like him.
