well, there was a dev competition where the winner did the storyline in something like 3 hours.
75 hours seems about right for a regular player intent on completing the scripted story line.
But there is that 'infinite quest' system based on your unique progress in the game, so im sure it will last much longer for some.
Anyway, after all, its only a single player game... eventually I will want to go back to games that I can play with friends, there is only so much entertainment AI challenge can be... so 75 hours for me sounds just about right. I dont expect to be playing it for years like an mmo
