Don't watch the trailer if you want to maximize your enjoyment of this film.  One of the things in the movie that I really enjoyed not knowing ahead of time, is given away in the trailer.  So don't watch it.

Here's what you need to know.  A struggling sports writer for a big paper gains inspiration when he meets a homeless man called "The Champ".  The Champ is an ex-professional boxer decades past his prime, played by Samuel L. Jackson in what I believe to be his best performance ever.  In learning about The Champ, the writer (played by Josh Hartnett, from "Lucky Number Slevin") learns about himself and what he needs to succeed in life.  It's a movie about values, and knowing who you are.

I give the movie 9.5/10.  Well written story.  Well written characters and dialog.  Superb acting from everyone.

I would agree it is a surprisingly good movie. I have to admit I was mentally think "great another movie about a sport hero-wow[sarcastic]", when I first heard about it. I would give it a 9/10 too.