I love games with a water motif so I'm interested, but it's a "Maybe" because... well, do I really want to play 5 games (3 of which have been heavily criticized) in order to get the full experience? I doubt it.
"Dyin' is easy. It's the livin' that's hard..." Grim Reaper, Maximo vs. The Army of Zin
Maybe. It depends how many missions require you to control the ship, and where the story goes. If they don't continue the story where AC3 left off (the first civilization stuff) then I'll be disappointed, and the ship battles were just ok. I prefered running around and killing people more than the ship battles. No matter what I won't buy it until it's $35 or less, which shouldn't be a problem considering AC3 was $35 on Black Friday after only being out for a month.
Problem with AC games isn't just declining quality. In AC3, they took out the last sections of the game and dlc-ed it for 30 dollars. They took out the original Desmond sequences and made it into Watch Dogs.
They don't do a good job on their game, yet they want to nickle and dime us customers. There are plenty of games out there where the developers put in great efforts into, and that's where I'll be spending my money.