I don't know if this was answer in book in the past (too many to read), I'm having a hard time figuring out whether this is an alternate universe from 616 or not. Things that make me think is it are it seems like Spider-man was cracking jokes like the old Peter Parker and not like Peter "Octopus" Parker. Also the image of Beast that we've seen looks like the pre All-new X-men Beast. Now what really has me confused is that there is a Superior Spider-man tie in issue and Dan Slott on Twitter today "Superior Spider-Man IS the Spider-Man of the Marvel Universe in ALL the 616 titles. Can't be any clearer than that. :-)" So which is it? Anyone know?

I sure hope it takes place in 616, but I honestly couldn't say.

The comic will probably reveal it in a later issue.

Bendis said it's cannon, so yeah.

Does cannon mean 616 or cannon in another universe?

It does not make sense for this event to take place in 616.

This explains it:

Marvel has stated that all art for the series was completed before it was solicited, ensuring deadlines are met and that there will be no more than ten tie-ins to the four-month event.

http://www.comicbookresources.com/?page=article&id=42269

There will be some way to reverse it. Too much devastation and character death for it to wind up in the 616. Whether it's an alt-U (e.g., Age of Apocalypse, Days of Future Past), an alt-timeline (shrug, most alt timelines become alt universes in Marvel), or a pocket universe (e.g., Age of X), we'll have to see.

Thor is going to fly around the world backwards in the last issue.

As much as I find the killing of Black Panther very....amusing after AVX, I'd prefer the Marvel U to try to remember its based on our world and it not post Worldstorm Wildstorm.

Yes.

It took place right after Avenger's 12.1 so before Fear Itself.