This is really one of the best thing I have read this year. The movie will be directed by Matthew Vaughn, who just made the Nicholas Cage vehicle, Kick-Ass, also based on a Mark Millar comic. (Vaughn was the director of Stardust)
Mark Millar's mainstream stuff can be hit or miss, but this is simply mindblowing.
Roots: Saviour, one of Millar's earliest works from 1989.
So go get the new edition put out by Image or if you are really lucky, try to score the original 2005 collection from Dark Horse.
Can't wait for Pt II.
[reminds me of True Faith, another early story from Garth Ennis from 1990. what's with these brits about faith, talking that long walk and the antichrist? see preacher, just another pilgrim, chronicles of wormwood...]