Ok, first let me say that i don't intend to write a review on Reygadas' "Battle in Heaven", as the film seemed to adress too many important issues in a complex way, so that I don't really feel up to the tasc. Similar to my not being able to review Godard's Notre Musique (2004). 
I mention this film, because I think they have much in common regarding their structure as well as being the two most explicitely political films I have seen this year. That said, I also think that Reygadas' film is vastly superior to Godard's effort and also has a sense of humor which points to Godard's work from the late 60s. Now I love Godard's films, he is one of my favorite directors, but somehow I couldn't fall in with the praise of his latest, as it seemed too much in-the-face to me, and didn't have to say much new. Now the same could be said about Reygadas' film, but I think that the execution is more multi-layered and succeeds in more aspects. 
Anyway, i don't particualrly want to start a discussion about these two films and directors, but through adressing them I generally wanted to state my opinion that Reygadas' abilities as a filmmaker may be in the same league as Godard's (though of course he may have to prove this in the future).

My personal rating of Battle in Heaven corresponds with Howard's (88 out of 100, which is an A- in my book) and I also agree with everything he wrote. Besides that, I'll mention a few things, and maybe we can progress in our discussion like that.

When the movie started with the blow-job and ana shedding a tear, i thought to myself that this film would be a let down. The beginning was very pathetic and not to my liking. But after the first 15 minutes which seemed a bit like an excercise for its own sake, everything fell into place, and the beginning revealed its qualities. At the end when we return to the blow-job, which imo hasn't a direct link to the story and serves more like a framing, Reygada's intentions have been made clear, and the victim/perpetrator dichotomy has been erased. You can call the ending cynical or nihilist, but I'd call it realistic with a wicked sense of "humor", one that makes you choke because laughter doesn't offer any release out of the world depicted. 
What I like about the film, is the fact that it doesn't have a "story" at all, and anybody expecting a plot which will make sense will be disappointed throughout the film (maybe that was trevor's problem?). Imo, every scene in the film is allegorical and has a lot to say about the mexican society and the human condition in general as well as the cinema and its devices. Basically it is an attack on preconceived notions and false excuses, which also comes along with its own critique. It satirizes a lot of its own attemps at false consternation, when reality is always much more complex and unsettling than any personal point of view. Interesting enough none of the characters are depicted as good or bad, they simply just are, as reygadas seems to observe some "models" of people in mexican society. The two main actors also use their own names in the movie, which imo makes the point, that none of us is excepted in this critique (not even reygadas himself!)

My favorite scene in the movie is probably the surreal moment when Ana and Marco meet an old man on a wheelchair outside of the brothel/home who is being taken care of by a foreign(?) nurse. Only through glances and one english line there are so many things expressed in a short time period, that it becomes a stunning example of reygadas' incredible abilities as a filmmaker. And this may actually be the single tongue-in-cheek meeting between marcos and his ever-present "Boss" who naturally is never revealed in the movie. Past, present and future completely merge in this scene. 

And one last thing. Finally a filmmaker who treats sound as equaly important and deceptive as the image. Another lesson learned from Godard. 

Now I'm really interested in some of your opinions, especially arsaib's negative take. Maybe you were repulsed by what one could interpret as Reygadas' distaste of the whole human race? Of course I wouldn't agree with that, as i think that some moments actually show not only concern for the people, but the director's love for his protagonists, even while he is condemning their actions. But maybe I didn't notice a couple of things.