The details about Assassin's Creed III are really getting better and better. We love the Wolfpack co-op mode and obviously scalping slave owners and redcoats with a half Native American hero is going to be the core fun. The way ship battles come off in this trailer from gamescom though looks absolutely amazing.
Pirate games focused on tall ship battles, swashbuckling and all of that have a mixed history. Even the ones done well (including 2003's Pirates of the Caribbean) can be disappointing when it comes down to it. I think instituting ship-to-ship battles as part of a larger game with a different type of gameplay might make both elements stand out more.
All I can say is Assassin's Creed III has put on a good show from the beginning and October can't get here soon enough.