It's heavily based on the book with not enough subversion we'd come to expect from a normal Coens film. At the same time, they maintain they want to do something new and fresh, but they can't shake off their 'signature' and thematic similarities as perceived by their fans. :D
About NCFOM - Cattle gun was used in the book as well. And that's quite an unfashionable device. It's an effective weapon as it leaves no trace of bullets (when asked abut it in an interview, Coens cheekily put it as "It gets the job done."). But as Feddy noted, he also carries a silenced gun. And imagine the stupid haircut to a Pantomime-like figure, with a husky voice reserved for obscure musings. And the killings weren't "cool" either, it was quick, and dark. Chilling is the word. Kudos to Deakins cinematography, as it is in deed 'grim' as he wanted it to be. but the chase and the events (notably the setpieces) were done in an engrossing manner.
About the 'psycho', I read it a bit differently. His philosophy of killing people has more to it - while there is no verbose moments to present himself as Joker and Hannibal Lectur, Chigurh looks down at his victims. He thinks of himself as a superior being. He would only give them a chance of a toss to spare their lives. Humans use bolt gun to slaughter cattle, a lesser being. In a similar metaphorical way, Chigurh uses it on 'lesser' victims to relieve the pain of existence, which he deems insignificantly piffle.
Btw Coens are exact opposite of "I need a cool way to kill people". That's more up the alley of QT's "Natural born killers" personifications, especially Kill Bill, which by the way we all embrace and love. NCFOM is pretty uncool.
