Just saw this film last night with my wife. We agreed that it went along very much with the book, and thus, with the facts of the case--as much as they could present in a two-hour (minus commercials) movie.
A great, detailed, fact-filled book such as Case Closed by Gerald Posner, would take more time on film than one of Ken Burns' films. I kept thinking--"Oh, they didn't put in this activity", or "They omitted this element of the story." What we saw were some family images of John Kennedy and his wife, along with Bobby Kennedy. I thought the two brief scenes of Bobby being telephoned about the shooting were particularly well-done. We saw him picking up the phone and being told, then after another brief scene, we saw his reaction, demonstrating his love for his brother. What was so good was that we didn't linger on his reaction for 5 minutes or so. It was brief, and that let us feel the moment without staying so long we felt embarrassed.
If you loved JFK, you saw some nice tender moments with him and his family. If you hated him, you saw some of the bad parts of the man. These were done in understated, not titillating ways. If you are interested in an accurate portrayal, you got to see positive and negative JFK.
A big feature was the detailed portrayal of Lee Harvey Oswald. His is the character we generally don't know enough about in terms of understanding what made him do the things he did. The film deals with his moving to the USSR, then finding out he hates it over there too, so he and his Russian wife move to the US, where they have a rather unhappy life, so much so that Lee spends many months living apart from her, visiting the tiny kids on the weekends.
We saw a bit of his activities in New Orleans and his impulsive appearance at the Cuban embassy in Mexico City, where he tried to get permission to move to Cuba. Oswald's attempt to assassinate an American General was shown as well, believing him a big enemy of communism. Later, we saw a very vivid depiction of the shooting of Officer Tippet and the way the police swarmed into the theater to capture Oswald.
The point wasn't to try to bring out facts unknown to people, but to put these things together in a way that lets the reader (for the book) and viewer (for the movie) know the people involved better than before. For anyone who doesn't know a lot about what happened, this is a way to learn much in just a couple of hours.
I found no weaknesses in the actor portrayals, nor their looks compared with the real life people, with one exception. We both noted that while they identified the main characters with a picture of the actor/actress beside a photo of the real person, they chose not to do so with Francis Guinan and Lyndon B. Johnson. We figured that is because the actor did not look that much like the politician.
On a typical Sunday evening, after all we have done in a typical weekend, it would not be odd to find one of us nodding off while watching a movie. Neither of us got the least bit sleepy during Killing Kennedy. Given that we both knew in detail what events were going to take place, I'd say that proves it was an excellent film.