I can usually spend about an hour playing a game before I feel the need to get up and do something else. That changes when I get my hands on any RPG or strategy game that I really enjoy. The Elder Scrolls games get me every time. When each those games where released I could burn 4-6 hours, no problem. Same can be said for the Civ series and most Paradox strategy games, like Europa Universalis.
I understand that backward compatibility is a big deal for some, but I'm not going to lose sleep over it. I only have a handful of 360 games and if I ever do get the urge to play them again I'll just hook up my 360 again. I really don't see that happening, though.