Oliver Stone used to make more compelling movies. In his day he had a way of making an argument (his films ways felt like closing arguments in a court case) in a way that not only convinced you but had you waiting with baited breath on the edge of your seat. Like with his last "political" film W., Snowdon goes through the motions of telling the story and making the case, but doesn't have the lust for life that his earlier films did.
That doesn't mean Snowdon isn't a compelling film, entertaining to watch. It doesn't mean that he doesn't make a fairly strong defence of Edward Snowdon. He does all of that. And Joseph Gordon Levitt's performance is spot on, not just in imitation of Snowdon's mannerisms but in his understated growing sense of dread and his morphing into strength. Stone and Gordon Levitt both succeed in what they are doing.
What's missing from Snowdon is the sense of urgency, passion, and the creative originality which made films like JFK so friggin irresistible. One might argue he is maturing as a film maker. In this sense I'm not so sure that is appealing. I used to watch his films expecting to see something I'd never seen before. Now I feel like I'm watching a good television dramatization. There is a disconnect between my passion for the issue and my passion for the film.
Perhaps one could argue that the film captures Snowdon's own temperament. In his interviews and appearances he always has that almost stoic, nerdy awkwardness. He doesn't exhibit the eccentricities of a Assange or the showmanship of a politician. Perhaps stone should get points for making a movie as monotone as its subject. I'm not coninvinced that is the best way to make this film.