I really don't know why all the aging fanboys are bitching about the return of the DC Multiverse in 52 #52. The problem with the original multiverse was that A) there was no clear point at which Earth-2 history ended and Earth-1 history began, thus breeding confusion on which Superman or Batman was which, etc., and B) they needed to come up with a convoluted explanation for how any given JSA'er was teaming up with Captain Marvel or the Freedom Fighters or whatever.
While I can see B) being a problem sometime down the line (expect a Crisis in 40 years to explain why Black Lightning III and Grunge are partying with the Justice Organisation of Canada on Earth-33), A) is already taken care of. The DCU's timeline hasn't been altered whatsoever here, and despite the superficial similarities to pre-Crisis worlds, the new Earths are all completely new.
And besides, the concept of alternate universes is a staple of the super-hero genre, and for 21 years, DC has had no structure in place to support that. The Multiverse is a vital part of what makes DC DC.
Welcome home, indeed.