Having skimmed through the script some initial impressions.
The script does a great job of capturing the character of Jonah Hex. The way he speaks, his sense of humor, his sense of justice, everything. It's spot on. You can tell Neveldine and Taylor just love Jonah Hex.
It's very violent and profanity abounds.There's really no sustained lulls in the screenplay.
The script has no more overtly supernatural elements than are regularly seen in Jonah Hex. The rumored zombies appear, all two of them, but there's a perfectly mundane and twisted explanation for them.
It's very funny at times.
They cover more of Hex's back story than I thought they would, but everything they include is relevant to the story at hand. There's a change or two, most notably in how Hex gets his scar, but everything they change is at least consistent with the character of Hex. They handle most of this information as short flashbacks and space out the revelations for maximum effectiveness.
The main villain, Quentin Turnbull, is an actual character with the same backstory from the comics.
On the negative, it's a bit cartoonish at times and nobody else is remotely as fleshed out as Jonah Hex. The main villain has a perfectly justified reason for hating Hex, but it's undercut by making him almost one dimensionally evil. Sure, depraved s.o.b.s are a staple of Hex, but it's really amped up here with the various villains being of the ****e disfiguring, dog killing, and mother and baby killing variety.
Still, as an adaptation, it's one of the strongest initial drafts I've read lately and I can picture exactly the movie they have in mind. Not the deepest, but definitely a fun one with a memorable protagonist.