Okay, I'll say it, since no one else will: I hated All-Star Superman.
Face it, Morrison's A-SS is full of crap. Oh, sure there are some outstanding "left elbow" moments... the one-page origin; the gooberness of Jimmy Olsen, Clark's entrance to the Planet. But overall it was a relentless spewing of Morrison's ideorrhea, with giant test-tube babies, yoctospheres, "fear genes", and some scientist who's apparently the love-child of Willie Wonka and the Rainbow Raider.
"But Morrison captures the joys of carefree silver age age blah blah blah."
No. He does not.
Yes, the Silver Age was characterized by a proliferation of wacky ideas, concepts, and characters. But the Silver Age was mercilessly rigid in following through on the ramifications of those ideas. Everything was explained (usually in long expository balloons), and if there were Superboy robots, then by all that is holy you had to explain it every time Superboy didn't use them: "Ordinarly, I'd use one of my robot replicas to fool Lana! But they're all off performing super-rescues or in repair at the moment! I need another elaborate and unlikely plan to protect my secret identity before Lana opens that door!"
In short, the Silver Age had the mentality of a child: endlessly inventive but very strict and hidebound about rules. Makes sense, of course, since that's when comic books were still written for children.
Morrison's writing, in contrast to the Silver Age, shows ZERO interest or concern for the logical ramifications of the concepts that litter his stories like mental fewmets. Wait, wait, you're trying to tell me some whacked out candy-coated scientist is farming all manner of freakish slave-like sentient organisms using Superman's DNA and -- and everyone's okay with that? That's the kind of person Superman used to capture, not save! Forget all about Superman and Luthor; who cares about them, when this Dr. Moreau thing is the REAL STORY?
Morrison dazzles you all by throwing verbal paint on canvas and quickly moving to the next one, while you gasp and stare at the multicolored Rorshach test, groping for meaning when there isn't any. If it's one thing I've learned from my professional careers, it's that great ideas are extremely easy; following through on them isn't.
That's why I'm no longer impressed by Grant Morrison.