There's no nuance here Inarritu pounds his message into you. In Inarritu's world, all authority figures are to be justifiably feared, as they go around beating everybody up and pulling guns on innocent people. People are mean to one another, some are unbelievably callous (I didn't buy for a second that the group of tourists who accompany Brad Pitt and Cate Blanchett's characters to a remote Moroccan village after Blanchett is accidentally shot would be so uncaring as Inarritu depicts them). But Inarritu makes this point within the film's first half hour - you only need see one or two scenes of this kind of frustrating verbal gridlock to understand what he's trying to say after that, the frustration just mounts without any kind of pay off.
"Babel" consists of a monotonous series of scenes in which people shout, storm, fight and talk over one another, always in a hurry to be understood without taking the time to understand. It's a conceit that greatly interests me, but Inarritu doesn't exploit its potential here. It's a theme that has engaged the interest of many a filmmaker lately - the idea that technology has made instant communication so much easier, yet people seem to be more than ever incapable of understanding one another. "Babel" is of course about communication, or more exactly miscommunication, in the modern world.
"Babel" sticks closer to the sentiments of the first film than the latter. I thought "Amore Perros" was so pessimistic as to border on nihilism "21 Grams" came closer to finding a sense of peace and redemption among the general human crappiness. Instead, he has painted a portrait of the world as he apparently sees it as a pretty bleak, uncaring and unforgiving place to live. This may have been his intention, but I don't feel that over the course of three entire films Inarritu did say much about these issues. Alejandro Gonzalez Inarritu appeared at the screening I saw and introduced his film as the final entry in a trilogy that includes "Amores Perros" and "21 Grams." Inarritu, in a comment that surprised me, said that his intent with this trilogy was not to focus on politics or social commentary, but rather to look at the modern family and what it means to be a father, son, mother, daughter, etc. I found it to be tedious and exhausting, and the effort I put into sticking with it far outweighed any sense of closure I received from it. Alas, it appears that, based on other user comments here at IMDb, I am in the minority on this film.