Milk was a good movie. Sean Penn gives a great performance, the rest of the cast is excellent, it's a well-made movie, and the treatment of politics is good. I'm glad they made it; it's a story worth telling, and they told it very well. Solid recommendation.
And yet...I couldn't really get into it, because it's just a pale imitation of a truly great documentary, The Times of Harvey Milk (directed by Rob Epstein). I don't mean imitation in a bad way, there; the biopic does well, and gets things right. But the documentary is just wonderful. It's especially good about representation. What the movie does is to reveal that descriptive representation (that is, an elected official sharing characteristics with constituents) and substantive representation (the elected official acting for, or on behalf of, constituents) aren't choices; they're two pieces of a larger concept of representation. Harvey Milk couldn't have been the politician Harvey Milk, the Mayor of Castro Street, if he wasn't gay; it was important for his constituents to see that piece of themselves in someone holding office. Yet he also was a great representative for other groups (the movie shows him acting on behalf of unions, Asian Americans, and seniors), despite not belonging to those groups. And what's wonderful about the movie (and, perhaps, what was wonderful about Milk) is that somehow his descriptive representation for one group helped him be a great substantive representative for a variety of groups. It shows Milk and the various groups as engaged in a continuing relationship, with one of the highlights of the movie being the (self-described) transition of a traditional union guy from being suspicious at best of Milk to ultimately having a strong, trust-filled representative relationship.
There's other terrific stuff, too -- Milk rapidly learned the skills of politics, and seemed to enjoy deploying them, whether for important causes or trivial ones. Of course, it's also terribly tragic, and for what it's worth I think the tragedy is handled even better in the documentary than it was in the biopic.
So, Milk: solid recommend. The Times of Harvey Milk: highest recommend. If you're interested in politics, and haven't seen it, you really should.