I think it's going to be the best yet, obviously. The game is constantly growing and expanding every new installment that Ubisoft releases. Judging by the trailers and the screenshots that have already been released, this game is going to top all the previous in nearly every aspect. Dual-wielding, and outdoor setting, hunting, Redcoats; nearly everything to be excited about! As well as the fact that the game is taking place around the Revolution and such makes it all the more interesting. I can't wait to follow Conner and the new Brotherhood on their newest and greatest quest yet!
I may just rent it if people I know say it's as short and stale as Brotherhood and Revelations. I play the AC games for the single player (multiplayer is okay, but I get bored of it quickly) and I beat Brotherhood in around eight or so hours including a bunch of side quests. I heard Revelations was a bit shorter, I've had it since December but only have played an hour and a half of it, just because not much has changed since Brotherhood and it gets very repetitive. So I hope they bring some new and interesting things in with AC3.