The term 'Over-rated' has become so overused it is now essentially meaningless. I mean that quite literally, whenever anyone says 'overrated' I have to ask them to explain what they mean as I cant tell anymore. They could mean that it over-sold relative to its quality, or that gamers give it too much praise, that critics like it too much, or that it shouldnt have won an award, or that people think too highly of it in general, then we get into issues like how each individual person has a different perception on all of the above, yeah the term has been completley done to death.
Part of the problem is that whether or not something is overrated relies on there being an understood perception of it ,and building a widely understood perception takes time, i would say that you should never apply the term to anything that has yet to settle into its place in the popular culture. If you are claiming something is 'overrated' within the week it came out? You are wrong, it's impossible to say at that point, as a general rule, if the game has been out for less than a year it is too early to say whether or not it is over-rated.