Portal 2 disappointed me. I mean, yeah, I almost cried at the end, but I left with a lot less than I expected from it.
In the words of Zero Punctuation:
"Portal 1 was, at heart, a puzzle game with a great framework. Portal 2 was a sightseeing tour with a puzzle game begrudgingly thrown in."
There were too many rooms where you walked around like an idiot, trying to find a tiny patch of white wall, only to move onto another room and do the same.