On the one hand, it presented a sort of capsule history of the civil rights movement. Also, along with the protagonist, I totally bawled at the end, when Barack Obama was elected. So moving, given all that came before.
On the other hand, while the film opened with 'based on a true story,' a bit of research shows that almost all the major incidents in the film (and even some of the major characters) are invented. It's less a biography of one man and more a sort of collage of many people's lives. They took a variety of real incidents which happened to a variety of real people and sort of collapsed them into one seriously fictionalized person's story.
On the third hand, as long as you keep that in mind, it's both a moving story and a good history lesson, rolled up into one. And Forest Whitaker and Oprah Winfrey gave stellar performances. Overall, I'm glad I saw it. Recommended (with the caveats noted above).
Also, as Kevin noted, the brilliant film _The Remains of the Day_ also features a butler caught in messy politics, a traditionalist and adherent of the old ways who finds it hard to change with the times, even in the face of terrible injustice. It doesn't have any of the racial aspects that make this film significant, but it's a better film overall, and notably less heavy-handed. So you could see that instead.