I agree with the comment that calling anything overrated or using the emperor-has-no-clothes cliche both imply that one's own opinion is the objectively correct one and that others have somehow gotten it wrong. So i don't think anyone can overrate a show or performance - if they liked it, they liked it.
There are shows that i have not been able to connect with as strongly as many others have. From this season, the biggest contrast for me was Fun Home. I only saw it at the Public and i understand that there have been some revisions and more interesting staging in the round, but the score and story didn't move me enough to make me want to go back and see it again, although i'm glad that i did see it once. My least favorite from this season was (by far) Honeymoon in Vegas, but that seems fairly typical judging from its early closure. From other seasons, my least favorite has been American Idiot. I also did not love Peter and the Star Catcher that way that many posters on here have, nor Billy Elliott.