Mariah Carey is brilliant in terms of range and intonation and technique and all that but she's probably one of the most overrated wailing banshees in music industry.
She always ends up "doing the Mariah thing" because that's all she can do. I'm not really a fan of divas like Whitney or Celine - but those ladies at least can put a lot more drive, heart and soul into that saccharine crap they sing.
Carey's style is very shiny and very polished but utterly devoid of substance or expression. Whenever the misfortune of hearing her voice befalls me, I immediately need a dose of Cave or kargyraa or Alexandrov choir...or death metal growling.