I'm confused by the bleak comments. Maybe it's becasue I'm northern but there's quite a few light-hearted moments to snap you out of the hard reality he's facing.
Freeman was impressive. Seeing as he's also the executive producer he was clearly confident about the role. It's such a huge risk performing outside your normal remit with a strong challenging accent on top. Especially for a southerner. If he did this to set out to prove something he clearly achieved it. Liverpool is a far cry from Middle Earth, Minnesota, Staines, Slough and Baker St.
I did feel they could have done with one more episode, a bit more mop-up of some aspects of the story, but I love these smaller series that get to the point.