It was ok... I honestly feel like the cut out way too many important scenes from the book. Calpurnia was barely there, the knothole scene with the weird music they played during it, and the scene where Boo Radley was introduced. They have this one scene where they spend a solid 30 seconds spitting at the fence, I counted.
That said, Gregory Peck, the man who plays Atticus plays him very well, so almost any scene with him in it is good.
Just because a movie is a classic doesn't make it good.