Now that the embargo is kind of broken I guess it doesn't matter anymore if someone just spills the beans. I'm not saying I'm from press.
The game is pretty much the same as the original not counting some story inclusions like Latios and Latias and the Primal forms. About the postgame, now that's what have people more curious about: all new megas have been revealed, no battle frontier, no new region or something like that, of course no new pokémon, etc.
HOWEVER the game kind of hints that things aren't complete when you finish Episode Delta. Some people mention that there's been reports of Pokémon reacting to megastones, some people simply namedrops the Battle Frontier as "something that's coming very soon", some characters that don't appear are mentioned in dialogues like Juan and Jericho. This doesn't happen until you have done everything story related. The game does have new areas to explore, some islands that in the original were just rocks or inexplorable islands are now filled with things to do.
Pic here happens when you visit Wallace at night (he calls you to go see him), there's a meteor fall when you speak to him. He says Steven is gone and that he will be the new Champion from now on now that you (the player) is busy living adventures. But when you go to the League, you don't battle Steven so the story kind of feels incomplete there. Which leads me to think that there is some sort of DLC coming soon or that the games are getting another version later.
http://boards.4chan.org/vp/thread/21764 ... game#reply