Did they really need to make a movie about this guy?
I've just finished watching this and all I got was the sense that Hoover was quirky but uninteresting. He didn't have family, there was just nothing of interest about him that required a movie making about him. You can get a sense of his life by watching other movies and piecing together what he did. Public Enemies, the Michael Mann movie, gave you all you needed to know about him. Maybe watch that four part Kennedy mini-series as well and you'll see all you need to.
Also, watch the Good Shepherd, there's a good spy movie with drama and intrigue. This movie didn't need to be made.