The Xbox conference at E3 said they're adding free mods like the ones on pc. So you can continue to play the game even after you've beaten it. Also my first play through of fallout 3 was probably over 100 hours. Personally from watching the fallout gameplay I've seen why it's taken them so long to make that game. They've added so much I can see a play through lasting much longer. But hey that's just my opinion.