AC4 gives you a character you can get interested in and a world that you want to see. It gets close to the light and likable moments of Assassin's Creed II and Brotherhood while giving you a big-ass ship with which to explore a vast world of piratical fun. It mixes in a little hunting and crafting, Far Cry 3-style. And it delivers solid cities with climbable points and enough different gadgets and items to make you feel intensely powerful. Not that you'd need much help in that department, since the combat is really just a flashy set of easily followed prompts designed to make you feel like some kind of raw, murdering machine. You know what? It works.
Wrap that all up in a world that manages to make fun of all the Desmond stuff in a way that almost makes me forgive them for messing up all the Desmond stuff as badly as they did and yeah. I'm back on board, Assassin's Creed. Congrats to the development team (all 20,000 of you) for picking up the ACIII mess and making something useful out of it.