During the editing process it was revealed that Irving's supposedly authorised biography of reclusive eccentric Howard Hughes was itself a fabrication. Welles added more footage and after a year of editing F for Fake was finally complete. How much of that origin tale is true is open to speculation, but then truth - according to Welles - is a flexible concept.
Aside from its technical wizardry and myth-exploding, the film is important because it gives us an invaluable insight into the artistic philosophy of one of the most influential figures in cinema history, Welles himself. Even through the smoke and mirrors, it's clear that this flawed genius is attempting to make a personal statement about the purpose of art and its role/his own role in the grand scheme of things.
This is the work of an old man facing his own mortality and wondering if his contribution to the world will stand the test of time. Some may regard that as self-indulgence, and for many viewers the film won't strike a chord, but if you're in any way interested in the man and his medium, F for Fake is a genuine masterpiece.