I've got to join with San in recommending this film.
Be warned: the story intentionally unfolds at a slower pace, so it won't be for everyone. The casting was superb. Some scenes were staged as well as I have ever seen. It was a transporting film -- that pulled me (which is rare).
There was some artsy camera work and effects -- but heck it got nominated.
In answer to the question above, I liked 3:10 to Yuma (finally, a role where I actually like Christian Bale) -- but I'll take The Assassination. . . any day.