The Yeti campaign to play through once and then stirred them even more because there is nothing more to achieve. About 10 hours of gameplay if you want to do everything.
The Durgesh-Mod has replay value, but is not much different from the main game. However, if you have the main game already by the remains of the only single player mode.
The multiplayer enhancements and additional weapons are hardly worth mentioning. Has short fun factor but you could prop integrate with the main game, just moneymaking.
Overall, however, but recommended for each FarCry fan. I have it bought for 30 euros. For 10-15 it is more reasonable.