Finished reading the book on which it is based: The Mystical Arts of Erasing All Signs of Death by Charlie Huston and it is a great read.
I can understand why Ben has gone for the lead part of Webster. He is in many ways so different from anyone I've seen him play before: a bit of an asshole on a downward spiral of self destruction who doesn't seem to care who he hurts with his acerbic quips. But he is also emotionally damaged, there is an underlying tragedy behind this persona which slowly unfolds through the story and makes for a really interesting character.
Really hope it gets made into a full blown series because I shall cry if I don't get to see it.