Marky-Mark Wahlberg stars in something of a return for him to Boogie Nights; he does the lower class aspirational thing really well, sincerely. I doubt he'll ever get an Oscar but this is probably his finest outing. In contrast Christian Bale got an Oscar nomination for his completely fake flaked-out rendition of the older brother, but that's just acting, there's no identification in it. It must be tough being professional.
I liked it. The boxing scenes were quite intense, communicated the violence and fascination to all comers (not just enthusiasts). Amy Adams does a solid job but ends up a little empty as she's too business-like. In some ways this is a lot like Trainspotting, but being set in America, it isn't much of a comedy but more a tragedy.
Dana Stevens loved it, as did Paul Byrnes. It is already parked at #211 in IMDB's top-250.