What really confused me was that the whole game I thought the ending would be you save everyone, your freinds fuck off back to civilization while you stay on the island as a mad god of destruction.
Finally finished Far Cry 3, probably a 9/10 for me.
Pretty much everything about this game was very good; great environment, great gunplay, lots to do, many ways to approach things, and it was a very solid endeavour all in all.
The one thing that was not good was the bloody story really. I liked the idea, and I liked the bastard characters, but the ones you're supposed to emphasise with and care about, I just found myself not caring that much.
I did like the revenge angle, and the overall feel of a descent into madness, but the ultimate pay-off was just not good enough. That last hour for me felt rushed, and not that satisfying. Rescuing your friends (the obvious choice) was the right way to go, but it didn't quite feel weighty enough for me. The 'side with Citra' ending was fucking terrible...just didn't feel believable to me, and smacked of 'need a shocking ending'
The story doesn't ruin the game for me at all though, this game felt appropriately suited to that slight b-movie schlock feel.
Co-op was also a lot of fun too (not tried MP though).
I thought it was all building up to that, instead you get two stupid options that made no sense to me.