That's about 2-4 days of fun should you not rush through the game.
We're talking about sitting down and actually playing the game, not the period of which you play it over.
10 hours of gameplay really isn't long but its today's standards really. So in Australia you pay $100 AUD for a game that lasts 10 hours, thats $10 for an hour of entertainment. Really isn't worth buying games from the stores these days. A game that gives you 20 hours of gameplay is much better, MP really can't be timed on how much you play because its designed for players to do the same scenario over and over, depending on the person that can vary extremely.
If I get 100 hours of MP game play and 12-16 hours SP I'm usually happy with my purchase.