Note, it's not intended to be about films you've walked out of. I'm not thinking of bad films, nor stuff like Matrix, Batman, Harry Potter, LOTR, Hobbit, etc etc (that sort of, um, distinctive thing tends to divide anyway, and they may not be your thing)
The stuff I mean is like the suggestions of Shawshank Redemption, Lost In Translation, The Piano, even the original True Grit - you don't dislike them, there's nothing that you'd point to as not working or poor. As I said, they don't suck. They're ok... but it's just that you don't see why they get such high praise.
Edit: to add The Piano. Exactly the sort of film I'm meaning. Something that might leave you feeling that you've missed something somewhere.