Fantastic, indispensable expansion, with more of the main game's open world gameplay loop, added a little variance.

Just short of perfect because it should've been more integraded into the main game; also, the story of what Jin's clan did on the island should have been referenced on the main campaingn.
In general, the expansion explores some of the protagonist's character facets, with him reflecting on his past and legacy, adding to his internal arc on the main plot.

If you liked the main game, this one is good too.
Played it in a continuous journey between one of the final chapter transitions of the main story.