Well, I think it's important to take into consideration that if someone says that something you like is overrated and fails to follow that with a "but" statement, showing that though they feel it is esteemed to highly it also has its merit, you would be inclined to go on the defensive since the statement by itself is, in fact, an insult. And if it's not an insult, it's most likely a way for someone to feel clever when they say that they weren't saying it was "bad", just "overrated" (By the way, OP, I'm not saying you're a jerk who thinks he's clever or anything; just that if someone were to say something were overrated as their sole argument in a debate despite liking it, they most likely would be planning on trying something like that... if that made sense...).