Honestly, the whole "they never read the book," criticism doesn't hold any weight with me. It's nice when they do, but with a combination of good script, director and the right actor it shouldn't matter.

If you think an actor did a poor portrayal of a character, it's not always the actor who's necessarily at fault. Christ, just look at pretty much every talented actor in the Star Wars prequels. All of them were awful in those movies, but I doubt they had much to do with that.