Was it the best ever? No. Will I watch it again? Certainly.
After having read the reviews, I braced myself for falling asleep in the middle of the movie, as it was late, I was tired, and I knew I wasn't going to make it through a "slow" movie. I didn't nod off once.
Its beautifully shot and acted, with a western pre-packaged plot turned on its head, a horrifically dry sense of humor, and a touch of magical realism (enough that they can get away with crazy plot holes, you just take it for granted that this world works just a little differently). Frankly, I'm convinced that those who perceive this as slow only observe dialogue and fight scenes in a movie. Yes, there are long scenes with long periods of quiet, but in order to keep this western sparse enough with words that you actually believe the narrator is the sort of fellow they claim, they do a lot of their storytelling silently. When you see the two characters riding, look at their horses: the outlaw rides his horse with it's head held relaxed, the kid's horse has his head straight up in the air, and gradually lowers it throughout the film, showing how up-tight the kid is in comparison. After one particularly disturbing gunfight, the outlaw whistles as he rides his horse, and the kid glares at him, then the camera pans around and shows the outlaw clenching his fist and rubbing it on his trousers - obviously feeling unclean. There's also some great visual puns/metaphors throughout, two in particular involving salt and horseshoes.
Watching it with an eye for these unspoken details, I became deeply invested in the story and characters, to the point that the ending (both tragic and hopeful) made for a painful emotional rollercoaster.