I've been a long time fan of the series, ever since the second games release which BLEW MY MIND. And though, Brotherhood and Revelations weren't NEARLY as good, they were still fun. Although, I'm completely sick of Ezio, and Revelations was pointlessly a rehash with literally nothing new added in, so I'm excited for this game and whatever it brings. People complain about it already even though we know nothing about it. And, like Munchy said, there won't be as many cool architectural things to climb up, but, although I love the parkour segments, that's not what the game is about. It's supposed to be about assassins, so hopefully, this game will expand upon the stealth sections, and make it more than just sitting on a bench, or in a hay stack, waiting to make your assassination. Changes to game series are often good things. Sure they go wrong sometimes, but I don't see that happening here. Maybe it won't be to everyone's likings, but that can be accepted of any entry into any franchise.
TL;DR It looks fun.