This game is mint!!
Honestly you could get lost in this game several times evan after playing it for a week strait.
Without the expansion packs your looking at 15 hours just for the story quests, that doesnt include all the side quests and general walking and killing (which is rather fun to shoot a fast animal and watch it fall).
Add ontop of thatthe expasion pack and you could be set for a very long play time.
Well worth the money!!