Llewyn Davis comes off as if the Coen brothers had written a Woody Allen protagonist - Laconic, neurotic, and often cluelessly offensive, his droll acceptance of life as it is can be just as frustrating as it is entertaining. Tragic flaws are very common amongst protagonists these days, but Llewyn Davis is in the unique position of having his constantly shoved in his face while he dutifully ignores it. Before the start of the film, Llewyn Davis is crippled by melancholy, but isn't reacting in the way most movie characters do - he goes on with his life simply because... he can. His very short term problems (finding a neighbor's lost cat, getting a temporary gig) don't have much weight to them because he isn't somebody who takes his responsibility seriously. By the end of the film, there is no clear indication that he has changed, but every indication that he is fighting against change on an almost subconscious level, stranded in a purgatory of his own devising. This is a hard type of character to make work, and that the Coens and Oscar Isaac managed to make Llewyn Davis such a lovable lost soul is a tribute to their combined talent.
Self-evidently a man who writes for the Internet, Robert also writes films, plays, teleplays, and short stories when he's not working on a movie set somewhere. He lives somewhere behind the Hollywood sign.