I was recently at the Toronto Public Library's Merril Collection of Science Fiction, researching 60s Superman comics for a lecture I'm going to be giving in January. It's hopelessly hokey stuff, but I can sorta see what Grant Morrison was drawing from when he imagined All-Star Superman - a naive and hopeless optimism that was much-deserving of the mockery it's received in the past couple decades, sure, but one that has a certain charm nonetheless. And if that naive optimism could be lent some depth and recuperated somehow...
It's tough to know where or how to start whenever I have to reflect on each issue of this series - and it only gets harder with this being the final issue of the best Superman story I've ever read. (And yes, I've read "Whatever Happened to the Man of Tomorrow?") Linking it to kitschiest bits of Superman and claiming that Morrison and Quitely have not simply embraced The Big Blue Boyscout aspect of the character but made it enjoyable, well, that's one way to do it. Another would be to note how the characteristic meta-moment Morrison slips into every ultimate battle scene is particularly effective here: Luthor, realizing that he's squandered his genius, stares out of the panel at us and explains that "it's all just us, in here, together. And we're all we've got." Hilariously, and poignantly, Lex precedes that revelation with "this is how he sees all the time, every day". "He" is ostensibly Superman, but could also be Morrison and/or Quitely or us. (Assuming, of course, that the reader is male.) And so what Lex, the would-be world conqueror, realizes is that he's a character in a comic book. (And maybe he thinks that he's "just" a character in a comic book. It's implicit that Superman realizes his fictional status, too, but he also seems to understand that he's not "just" a fictional character - that there's power in his existence - and that its fictionality doesn't necessarily diminish the meaningfulness of their battle. If Lex is made to feel insignificant by the realization, it's because he's a pessimist, a skeptic, and a megalomaniac.)
Perhaps the most impressive thing about this final issue is how Morrison and Quitely manage to meld the ubermensch, the proletarian, and the Christ into one figure - only to discard it. They deliberately invoked Nietzsche in issue 10, they give us this wonderful shot of Superman in the heart of the sun that I know is paying homage to a Communist poster that exists but that I just can't find**, and they have Superman die and be returned to life by his father to finish his job before finally ascending into the sun. And for all of this deification of the character, they tell us in the end that the world doesn't actually need Superman - that good super-geniuses like Quintum* already exist to oppose the evil super-geniuses like Luthor, and that humanity can achieve something super all by themselves. Further to that point, it's telling, I think, that the iconic image of Superman I described above is not the final page of the comic, but that Quintum gets the last word and the door to his Superman 2 project is the final shot of the series.
The "world without Superman" cliché has always indicated darkness and disaster when DC attaches it to company-wide events. But not so here. At the close of All-Star Superman, it simply presents an opportunity for humanity to show that it was worthy of his protection in the first place.
* (Added 9/25: In the comments, james provides a link to an excellent discussion of Leo Quintum, which parses some obscure textual clues that would seem to indicate that he's Lex Luthor, having reformed and traveled back in time. And this revelation only makes an incredible story even better. I won't repeat everything the article says or add much else - it probably deserves its own post - except to say that I'm going to have to re-read the whole thing with that in mind.)
** (Added 9/26: A post at Comicboards' Superman MB suggested a similarity to Soviet artist Evgeniy Vuchetich's "Let us Beat Swords into Plowshares", which is displayed at the UN in New York. There's a certain similarity, though I'm not sure it's what I had in mind. The sentiment, though, totally works.)