[Neil published a smart post in this subject on his blog. Below, I have reprinted the conclusion. Click the quote to go to the full post (not a long one) on his blog. My only quibble would be that I think Morrison wants to revive the league of Batman, wants to show them as not lame -- he just fails for the most part].
For all its seeming genre-playfulness, the story is impossible to actually submerge yourself within. As Batman remains critically, even patronizingly, distanced from the exercise of the story, it becomes difficult for us as readers to feel anything for - as Robin described them last issue - the 'league of Batman impostors'. It's an ironic revision of a terribly lame concept that supplies us with equally lame motivations for the villains and does little more than convince us that, yes, clichés and Batman impostors are, as I said, terribly lame. Didn't we already know that?