What makes Castaldo's essay so good is that she doesn't spend time gushing over how wonderful Sandman is, and instead gets right to brass tacks about what Gaiman is doing with Shakespeare. Other writers are content to just sort of handwave, for example, Gaiman's extremely liberal use of facts and his willingness to use long-refuted anecdotes about Shakespeare's life as fact. The most obvious of these, for example, is the "Prospero is Shakespeare's 'me character'" conceit, which we all know is complete bullshit but which we all like to pretend is true because, dammit, it makes a great story. Other writers pretend it is true, or they admit its not true but pretend it is. Castaldo allows it is not true, admits Gaiman knows its not true, and then goes on to the better question: When Gaiman uses the story as if it is true, what it is saying about Gaiman?
So this article is a wonderful examination of Gaiman's choice to use Shakespeare as his personal surrogate in the book, and it helps shed light on what Gaiman might be trying to say about himself and about Sandman the comic series. Castaldo understands that Gaiman isn't as original as everyone claims. That he kind of dislikes his own books after they've come out. That Gaiman seems generally uncertain about his own life's work, and about his success, and even a little guilty, because he knows he's using all these old characters and concepts which have been around for years but which everyone seems to act like he made up. That is, there is a wonderful ambiguity about Gaiman's self-presentation in Sandman; she has helped me to understand that Gaiman isn't using Shakespeare to puff himself up as a (indeed, THE) master storyteller, but is rather using a construction of Shakespeare, which he throws doubt and guilt upon, as a way of illustrating the doubt and guilt which Gaiman himself feels.
This is a wonderful contrast to Moore. I'm not entirely certain what to make of it yet, but I think it has to be significant that while Gaiman uses Shakespeare as his autobiographical representation, Moore chooses instead one of Shakespeare's characters. Shakespeare, himself, doesn't exist in League except as an offstage guy who wrote factual plays about things that really happened. The conceit of the Blazing World is that Shakespeare made these fictional characters, but the fictional characters in turn affect the real world, creating a sort of endlessly reinforcing loop of influence so that it is impossible to really say either of them are "real" or "fictional." So Shakespeare creates Prospero, who influences Alan Moore. Maybe Moore isn't so much using Prospero as a stand-in for himself, as he's revealing that he, Alan Moore, is something of a stand in for Prospero!
Anyhow, Gaiman's Shakespeare is a guy eager to lay his burden down. A guy who has sacrificed his real life in order to tell stories, and rues the bargain. But Moore's Prospero is just the opposite: he is a vigorous protagonist who refuses to give up his books, who stages his own death so that he can go on a secret mission to save two worlds. He's lived a life, a good long rewarding life as a Duke, a husband, a father, but I think he kind of rejects that life in favor of the Blazing World, a world of imagination made real. I suppose it's something of a psychedelic argument, and it would be easy to just say, well, Moore wants to give up reality for the Blazing World because he's doing a lot of Amsterdam hash, but I don't think I'll use that for my conclusion.