Figured I would bump this. Bought the game last night and only played an hour or so but here are my thoughts so far:
Ubisoft learned from the last game and start you out in the middle of the action immediately instead of a couple hours into the game. Naval combat has been tweaked a bit an improved. Better aiming and firing system plus a wider array of weapons make naval combat more fun. The world is really beautiful and Edward's story seems like it will be more enjoyable. I like Connor and the time period he was in but I think his story was just too dark and heavy for these games. The appeal of these games is the romantic thrill of fighting an Illuminati type organization and exploring the beauty of the landscapes. Connor's story was more about a lone warrior trying to fight against a genocide. Like I said...a little too dark and heavy. This game seems like it will appeal more to people as a romantic (as in Romanticism
) adventure in the style of AC2. Huge world with really vibrant color and cool geography. I think it will be a more enjoyable experience as the opportunity to explore dense jungles will be more appealing than a snowy frontier. AC3 was actually my favorite game but I definitely think this one will be more widely appealing.
The Desmond arc has been shifted into a first person perspective as an Abstergo employee using the Animus. That part is still tied to Desmond but it isn't an overbearing story arc forced onto us this time around. I anticipate that the first person experience will lead to snooping around Abstergo and eventually turning on the company as you unveil secrets in the present and through Edward's Animus stuff but it does a better job of not detracting from the Animus sessions.
Also, they seem to have simplified the menu system and made it easy to navigate which is a big bonus.