This plot had great potential but on occasions got lost and repeated similar violent scenes with the main protagonists. The director was uncertain how to get to the climax and just reincorporated failed attempts that he wasn't confident to discard.
Great photography and some good acting from three of the leads. However Andrew Lincoln's character voice of John speaking with a continuous monosonic back of the throat straining whispers in four or five word bursts,was not realistic and to negative dramatic effect.
Although Tommy ran off at the end, sanctioning a second series, you'd do well to give it a miss.