It was, by far, my favorite AC game. It was also extra awesome as it was one of my first PS4 games.Necroing this because I bought it last week for $6 on Steam and I think it might be one of the best games I've ever played.
I love the sea shanties but I have to admit this wasn't my first exposure to them. I played an indie game on Steam called Nantucket (a whale hunting card game, yeah you heard that right) which had all of the same ones from AC4, although AC4 has quite a bit more of them than Nantucket did, and I'm sure Nantucket got the idea from AC4.
There are still the two last 'Hard' zones for me to unlock in AC4 but so far I have not yet heard this Shanty, in which the full version which was in Nantucket.
Shit I always meant to get this one on ps4 as soon as it got cheap enough but lost track!