Quite enjoyable. I won't go into it, but it's worth a watch. Good casting and performances, nice production values, decent pacing and editing. Not terribly deep, intense, or anything like that—just good entertainment for a cold, rainy night. I like Edward Norton and Paul Giamatti quite a bit. The tension between them is not unlike Rick and Capt. Renault's (Louis) in Casablanca, which works.
I was unconvinced by the scene in which the Prince, Mr. Age-of-Reason but a total jerk, kills himself, but this opens up some holes so let's just let it be what it is. Watch it for pleasure and let the suspension of your disbelief work its magic.