10 hours gameplay? that's not much, is it?

No its not. But I went right through the game. Not sure if there are side-missions or not.

Sadly its pretty common these days for a game like that to be that short.
(I remember finishing the new Medal of Honor in around 5 hours)

edit: I think for 15 bucks it was ok. But I'm glad that I did not pay 40-50 bucks for Mafia II.