"Overrated" is an ambiguous term.
It could mean
(1) "overpriced": too much $$$ for the bang
(2a) "hyped" but nothing to write home about"
(2b) "taditionally considered good, but not really/anymore"

Thus, a popular el-cheapo supermarket series might be as overrated as
a micro-Chateau Garage. Moreover the benchmark for quality (AKA, the bang) may vary for each consumer. While I absolutely agree with violist (A 1982° Lynch-Bages in 2001 was one of my first great wine experiences), others would second Rejuvenated (probably (s)he opened a bottle from the latest vintage available ).

My picks (higly subjective):
(1) some CA Cabs, some Super Tuscans, Brunello from Biondi-Santi
(2a) Pinot Grigio, Beaujolais Nouveau, some atypical CA Pinots
(2b) Champagne. CAVE: highly subjective, I am not a bubbly fan. The Biondi-Santi may also fit into this category.

Conversely, my +ve list (also subjective):
(1) Riesling, especially German Riesling, Spanish reds.
(2a) also here Riesling, many Spanish reds
(2b) Barbera, Beaujolais (the Crus, not the noveau)

Admittedly, I started this post and then I had to think a lot...it is not that simple