A little list of popular titles that I feel are overrated.

Overrated Rating
FLCL (OAV) Very good
Gurren Lagann (TV) Very good
Gurren Lagann the Movie – The Lights in the Sky Are Stars Very good
Gurren Lagann the Movie –Childhood's End- Very good
K-ON! (TV) Very good
Neon Genesis Evangelion: The End of Evangelion (movie) Very good
Soul Eater (TV) Very good
Toradora! (TV) Very good
5 Centimeters Per Second (movie) Good
Bamboo Blade (TV) Good
Basilisk (TV) Good
Berserk (TV) Good
Black Butler II (TV) Good
Black Cat (TV) Good
Blassreiter (TV) Good
Bleach (TV) Good
Bodacious Space Pirates (TV) Good
Dragon Ball Z (TV) Good
Love Hina (TV) Good
Mind Game (movie) Good
Neon Genesis Evangelion (TV) Good
Phantom ~Requiem for the Phantom~ (TV) Good
(The) Sky Crawlers (movie) Good
Tokko (TV) Good
Tsubasa: RESERVoir CHRoNiCLE (TV) Good
Agent Aika (OAV) Decent
Android Kikaider - The Animation (TV) Decent
Angel Links (TV) Decent
Aria the Animation (TV) Decent
Blue Drop (TV) Decent
(The) Book of Bantorra (TV) Decent
A Certain Scientific Railgun (TV) Decent
Final Fantasy VII: Advent Children (movie) Decent
Final Fantasy: The Spirits Within (US CG movie) Decent
He Is My Master (TV) Decent
Memories (movie) Decent
Naruto Shippūden (TV) Decent
Neon Genesis Evangelion: Death & Rebirth (movie) Decent
Night Raid 1931 (TV) Decent
Penguindrum (TV) Decent
Texhnolyze (TV) Decent
Voices of a Distant Star (OAV) Decent
Ah My Buddha (TV) So-so
Dragon Ball GT (TV) So-so
Guin Saga (TV) So-so
Naruto (TV) So-so
Now and Then, Here and There (TV) So-so
Queen's Blade 2: The Evil Eye (TV) So-so
(The) Qwaser of Stigmata (TV) So-so
Arjuna (TV) Not really good
Gilgamesh (TV) Not really good
Metropolis (movie) Not really good
Pandora Hearts (TV) Not really good
Queen's Blade: The Exiled Virgin (TV) Not really good
Star Driver (TV) Not really good
Kiddy Girl-and (TV) Weak
Wolf's Rain (OAV) Weak
Gantz (TV) Bad
Jin-Roh - The Wolf Brigade (movie) Bad
Kite (OAV) Bad
Rurouni Kenshin: Reflection (OAV) Awful
X (movie) Awful