Just thought Id put in my two cents.
For me, Babel was definately a dissapointment coming from Innaritu, and I hate to make the comparisons to Crash but thats what happens when you try to construct a moral fable like these two films are. The movie ended up feeling like an overpolished story trying to be gritty, unlike Innaritu's other films which were raw and unrefined.
21 Grams for me was not an enjoyable movie, but my problems with that film lie more with the fact that its a 2 hour long hell ride with no redemption, rather than the actual direction of the movie. Innaritu got all the emotions right, which is why its not a great film, no one wants to go through hell unless its for something important (ex. Schindler's List)
I think Innaritu really loses something when he streches to far away from his homeland. For me, the nanny's storyline in Babel was the most intriguing because it managed to do what I think Alejandro was trying to do with the film, which is tell a great story while also dealing with contemporary problems. The topics of family, love, recklessness, they dont present themselves in the rest of the film without Innaritu beating are heads with political commentary first. He makes a bad choice when he focuses on the response to Cate Blanchett's shooting, it takes us away from what is really important which is the relationship between the couple.
Innaritu has forgotten that what made Amores Perros so great (and if you havent seen the film I highly reccomend it) isnt the fact that all these characters were connected, that was just a gimmick, it was the fact that it showed all of these relationships with their ups and downs and thats what I want to see. You cant make a political film without giving us characters we can attach ourselves to.