Gary Oldman is magnificent as Winston Churchill. He completely disappears into the part and if I didn't already know it was Gary Oldman, I'd never be able to guess. The movie is not a paint-by-numbers biopic, plodding dutifully through the highlights of someone's life, but instead takes place only over about a month or so in 1940, when things were not going well for the allies during World War II and difficult decisions had to be made. Oldman is completely mesmerizing to watch. For me the greatest strength of the film is showing how agonizing and difficult it can be to be the person at the top who has to make the final decisions in terrible times, knowing that people's lives are at stake.