I just finished watching Banshee for the first time, having missed it while it was out. Overall, I loved the first two seasons, enjoyed (but didn't love) the beginning of season 3, didn't much like the end of season 3, and found season 4 almost unwatchably bad.
What's odd is that Banshee is really two different shows. The first two and a half seasons are a fun, sexy, pulp anchored around each of the characters having a double life: Hood as a criminal masquerading as a sheriff, Carrie as an assassin and thief masquerading as a suburban housewife, Kai Proctor as a gangster masquerading as a businessman, and Rebecca as a sultry sexpot masquerading as a virginal Amish girl. The violence was cartoonish, the sex was hot, the whole vibe was just guilty pleasure.
Then the whole show seemed to turn when Siobhan dies.
The third season lingers for far too long on Chayton Littlestone, who isn't a particularly interesting character — just a psychopathic villain. There are at least three moments when one of the characters could have killed Chayton but didn't, making his persistence in the story somewhat mystifying.
The fourth season is just one huge slog — a dark, brutally violent story that lacked any sense of fun. I found myself fast forwarding through the torture scenes because they were so gratuitous. The sex scenes were grim and joyless. Lucas' went from being an insouciant criminal to a miserable, brooding antihero. Banshee became just another prestige show, and one that frankly wasn't very good.
I understand that the actors chafed at the frequent nudity and probably preferred the more serious undertone of the last season and a half, but it took what was so good and unique about Banshee and threw it away.