I have mixed reactions to this movie. My initial reaction was that my preconceived notion about movies -- that the actors' performances can make a bad movie good and vice versa -- were wrong. The performances in this movie were, in my mind, very good. However the movie remained, in my mind, not so good. I had high hopes for the movie for about the first 10 minutes -- I really thought I was going to like it a lot. Then, the story went asunder.
The biggest problem with this movie is the storyline. The conflict is not very well defined -- I'm still not quite sure what exactly the conflict was and why it arose. The relationship between Billy Crudup and Claire Danes' characters was not developed at all. You know right off the bat that she fancies him, yet they are to some degree enemies throughout the middle, then she suddenly cares about him again and helps him, and then they are passionately in love by the end. There were also a couple of consistency problems. For instance, the writer and director were on one hand clearly making a mockery out of some things (i.e, King Charles), yet on the other hand they seemed to shed a more serious light on other things (i.e., the importance of the role of the actor and the acting process). So for example in the movie there's a scene where King Charles is dressed in drag and it is clear that the audience is supposed to not be taking him seriously. Yet then Billy Crudup's character comes in to talk to him all distraught about his inability to act as a man. The dynamic in this scene was awkward. Another consistency problem was that for the first quarter or so of the movie, the characters were saying and doing somewhat crass things. I actually laughed at a couple of these instances and thought it would be comic relief for the movie, but then these laughable instances suddenly stopped and again it seemed like the writer/director were taking a more serious turn with the movie.
Depending on what your definition of a "good" movie is, you may like this movie and you may not. Personally I frequently found myself wondering why in the world things were happening and how the actions of the characters fell into any kind of sequential scheme. However, the acting itself was very good, the costumes, makeup, and sets were pretty good, and the cinematography was nice as well.