As others have pointed out, there are irritating problems with logic throughout the story. But I found the show clearly worth viewing - because the dialog was great, the premise was a good one, the acting and directing were outstanding, I cared about the characters, and the ending was satisfying.
The writing of a screenplay has a number of important components, and not every good writer is a master of all. David Wolstencroft was the author, and his dialog is very good, his character development excellent, the basic scenario good, his plot creativity good, his resolution of the story rather brilliant. His one fault, as I see it - and it's a big one for me - is believability. In order to advance his story, he resorts to plot twists that defy logic, and characters who act stupidly and have emotions that don't fit - and he does it over and over. A serious failing. I've often thought that every screenplay that wants to be considered as serious art should go through a logic evaluation process before screening.
Still, it was a riveting series, and I couldn't wait to see how it would turn out. I worried about some of the characters, the villain was memorable, and I loved the ending; it was so clever that a little implausibility there didn't ruin it for me.