That's a good point re: finishing the movie. I rarely if ever bail out on a film, so even if I'm clearly not enjoying it I make it to the end. Gangs of NY took me 3 tries to finish, though. The Departed was a light pop film, and because it was basically a beat-for-beat remake, it didn't really "feel" like a Scorsese movie, but it worked in its own fashion. To me, Scorsese's earlier work means you can demand more from his films than you could, say, if some brand-new director came out and made Shutter Island. Taxi Driver is in my top 10 films of all time. Mean Streets, King of Comedy, New York New York, Color Of Money, Raging Bull, Last Temptation = these tower over the works he made later.
I will re-rate the films:
Cape Fear -- pass
Age of Innocence -- fail
Casino -- pass
Kundun -- fail
Bringing Out the Dead -- fail
Gangs of NY -- fail
The Aviator -- fail
The Departed -- pass
Shutter Island -- fail
Hugo -- fail
Wolf of Wall Street. -- fail