I loved it - well, let me qualify that - thought the main story was terrible, with terrible (and overly long) cut-scenes, awful 'dream' sequences and way too many Quick Time Events
However, I absolutely loved all the side-questing, taking the red camps and controlling the island.
Finished the game and am tempted to play it again with mods that unlock all the weapons from the start and reveal the whole island, so I can just go around taking the enemy camps and ignore the main quest