Let's see, from the games i can remember now:
FEAR - Overrated as the scariest and coolest shootah ev34r. Ok, it creeped me out, true. But i was more scared in AvP2 (And i'm easily scared). As for the shooter part... Meh, those gun fights annoyed me to the point of quiting the game half through and watching the outro on YT.
World of Warcraft - no comment needed.
System Shock 2 - Fun to a certain point, then becomes kinda boring.
Gears of War - Just overrated.
Counter Strike - Unless somone proves me that every standard Anti-Terrorist action looks like a generic deathmatch with some ignored-by-everyone in between.
GTA 3, Vice City, etc - Crap imo.
(those are actually the only new games i played
(excluding HL2))
Hm, now that i think of it, i'd have to agree with Arch - Most games are overrated in one way or another.
PS.
I never played Halo though.