This film has an uphill struggle against all the hype that surrounds it, with David Fincher and Aaron Sorkin on board this should be the Citizen Kane of our generation. Furthermore nearly three hours of cinema about unlikeable characters building an internet business would be a tough sell at the best of times.
The actual films is somewhere between the hype and one's worst expectations. Until about half way it is worthy and impressive, but frankly a little dull, around the point that Justin Timberlake appears as a superficially charming pantomime villain, Sean Parker of Napster fame, it clicks up a gear, and becomes genuinely far more gripping fare.
The film does fall short in a number of areas, Fincher is for the first time shooting exclusively on digital stock here, and the cinematography is proficient rather than amazing, the script has most of the best lines from any film that decade, but at nearly three hours this is a long haul of a film. There is a narrative arc of sorts, but this is achieved by creating a pantomime villain in Parker and allowing Zuckerberg to become vastly more likeable in the second half than we had any reason to expect in the first half.
So, is it close to reality, probably not, is it a great film, not entirely, is it worth a watch, pretty definitely particularly if you like talky films about geeks.