Critical Reviews
If you look at the 14 metacritic reviews, they are 80-100 from the leftist MSM. Not surprising considering Poitras and Greenwald are Marxists. I look for reviews at well know libertarian/conservative sites and found nothing. So far I found one critical review and a short piece.
Sins of Omission (Fred Kaplan @ Slate)
Citizenfour is a fine documentary. Too bad the director glossed over some important details—and Edward Snowden didn’t gloss over more.
http://www.slate.com/articles/news_and_politics/war_stories/2014/10/ci tizenfour_review_laura_poitras_edward_snowden_documentary.html
Second U.S. Intelligence Leaker Referenced in New Edward Snowden Doc; Obama Painted in Negative Light http://www.theblaze.com/stories/2014/10/11/second-u-s-intelligence-lea ker-referenced-in-new-edward-snowden-doc-obama-painted-in-negative-lig ht/ [not really review]