GOOD THING: The art is a bit lackluster but the story is excellent. We go through Book's past in reverse, starting with his death in Serenity and moving back towards his time as part of Mal's crew, his time at the abbey he was leaving when we first saw him and beyond.
So what was his past? Like I'm going to spoil it here. But trust me - it explains some (but not all) of just how a simple preacher could know what he knows about the dodgy side of life and using a gun.
The Final Verdict: If we have to have the mystery of Shepherd Book's past spelled out, I don't think we could have hoped to have a better story than this one. Shame we couldn't get artwork the equal of the story, but if you can look past some questionable caricatures, it's not that bad.