How much of the depiction of the main character is fact, how much is fiction, is hardly important. Neither is the revelation that Sorkin admits to rigorous researching to bring verisimilitude to his lead character. This is a movie, after all, and must be judged as such.
It's easy to see how a self-satisfied, sometimes smug, sometimes shy fellow with brilliant electronic ability, could overcome feelings of decency or guilt, and dive full force into the upward climb to the top. His retort to the question, "But why do you do it?" is with a snappy, "Because I do."
High praise goes to Fincher's tight control over his cast, not only in the depiction of their characters, but in the use of a dialog spewed rapidly, continuously, throughout the film. No long pauses between speakers, no protracted scenes without brisk action (the stuff that kills the pace in most films today) - rather, a snappy pace augmented with snappy editing (Angus Wall, Kirk Baxter), a discerning use of camera (Jeff Cronenweth) accompanied by appropriately shaded music (Trent Reznor, Atticus Ross) and production designs that leap from nondescript campus digs to the Harvard scene, to California and New York (production designer Donald Graham Burt) - two hours of solid, suspenseful drama, not easily forgotten. (Grade: A)