Django Unchained doesn't reach the artistic heights of Tarantino's best films (Jackie Brown, Inglourious Basterds, Pulp Fiction). But it's a great movie about revenge, cruelty, brutality and love. Jamie Foxx is killer in the title role, doing his best work since Dreamgirls. He's icy and collected, with rage burning behind the eyes. Christoph Waltz and Samuel L. Jackson do what they do best and excel at it, creating vivid and colorful characters who are at once believable and baffling. Unfortunately,…