J. Edgar is good but not great
This is a slow-paced film shot in a moody, dim lighting. Leonardo DiCaprio does a great job with Hoover at the end of his life - you forget there's a much younger man inside. But for most of the film, DiCaprio's Hoover is shallow and without joy, an obsessive paranoid too long in the job, who uses the FBI's power to collect secret files and then blackmails whoever displeases him. But we never get the juicy details!
Director Eastwood has chosen to focus Hoover's emotional energy more on his love interest with Agent Tolson and his distorted relationship with his mother, and less on, say, how the FBI went after gangsters during Prohibition. You know, some action!! The guy who plays Tolson does a terrific job, but I don't get much entertainment from guy-guy love relationships. And Tolson's makeup as an old man is truly weird... frightening even.
So, had there been more roaring Packards and G-men with Tommy guns, more focus on the FBI itself, I would have liked J Edgar more.