Just to be sure I equipped myself with a Blu-Ray version of the movie and watched it last night with V. It was a strange, overlong experience in which the whole was definitely less than the sum of the parts, but some of the parts (especially those where James Gandolfini is present) are very good. Indeed the subplot involving Julia Roberts's relationship with Winston the homosexual hit man might almost have worked as a stand-alone concept, a feeling reinforced by the sense one gets that these scenes were actually overseen by a different director.
But as soon as Pitt and Roberts are together it becomes a very different film, a slightly goofy and hysterical action-comedy of the kind Mel Gibson was once inclined to appear in. Even then, one can look behind the star vehicle shenanigans and appreciate the contributions of a number of supporting thesps who seem to think they're in a better movie, and gawp at the authenticity of the Mexican setting...if not of the Mexicans themselves, whom Gore Verbinski portrays in much the same way as he would later portray pirates.
Other detachable delights involve on-going gags about a cemáforo and a chucho elécrico, plus a series of sepia-toned, Rashômon lite-styled flashbacks to the legend of the beautful pistol made for the nobleman's son.