Enter Filling the Gaps, a series about the films that you're 'meant to have seen,' that you never got around to (and when I say you I mean me, though more than likely you as well.) I will try to keep you unspoiled, and will undoubtedly fail. Complain in the comments.
After watching Sunset Blvd for the first time, I really had to reflect on why this was considered an all time classic; it's not that I didn't enjoy it, in fact I stayed up until 3 AM to finish it.
(Bizarre childhood confession: while this is the first time I've seen Bill Holden in a film, I am ashamed to say that my first introduction to him was in a very late episode of I Love Lucy, one of the really terrible ones, where he plays himself as a crush of Lucy and Ethel.)
Leaving that aside...
It's the earliest example I can think of in so-called 'canon' movies that uses a multitude of literary tropes: an unreliable narrator, in-medias-res story form, and most importantly, metafiction.
But, the greatest accomplishment of the film, without question, is getting former silent movies stars to put aside their egos and play failed versions of themselves in a 'talkie'.
What a rogue's gallery, described by our narrator as "The Waxworks": Norma Desmond, played by Gloria Swanson as a thinly veiled parody of her own career. Buster Keaton, looking almost skeletal, Hedda Hopper, Anne Q. Nilsson and H.B. Warner, amazingly playing themselves, as actors trapped on their pedestals even though their fans have long deserted them.
Cecil Demille also plays himself, in one of the most honest roles in the film, setting a counterpoint to Norma Desmond's delusions while William Holden's Joe Gillis is content to play along and pacify her. Until he isn't, of course. I do wonder, though, how many films since this one have hinged their final act on the hero suddenly 'finding a conscience.'
I'm not sure this is a movie that everyone would enjoy, but I certainly did, and it improves in my mind the more I think about it.
-"You're Norma Desmond...you used to be big." "I am big. It's the pictures that got small."
-"All right, Mr. Demille. I'm ready for my closeup."