Game length is a tricky thing, because (1) replayability is a fundamental part of gaming, and (2) making an action game longer than, say, 8 hours is really, really difficult. Max Payne, still one of the greatest FPS games ever made, was about eight or nine hours long, in terms of game-play. But it was so well done, you kept coming back for more.
Judging from the demo and reviews, Naughty Dog nailed it - they cut the action down to the core blockbuster suspense, and they created interesting, empathic characters, and ran with that puppy.







