Citizenfour has been reviewed just once.
Citizenfour (2014) - 9/10
I may end up on a list or two at the NSA or GCHQ for saying this but Ed Snowdon is a fucking hero. He basically took on the US government, knowing the risks to himself and those close to him. But he did it anyway. Why? Because he wanted to do the right thing and he believed in something. Others like Glenn Greenwald and Laura Poitras also have massive fucking balls. If you've ever owned a phone, had a bank account or used the Internet, you should watch this.