"Alternative metal" is just a euphamism for the much dreaded term "nu-metal." Regardless of what you call it, I detest this form of music a lot because it's a total reversal of the fundamental principles of the heavy metal genre, and that it sounds like shit.
Alternative metal is merely what happens when you strip away GOOD things about the heavy metal genre like intense song structures, guitar solos, well-written lyrics, complex drumwork, and quality vocalwork (whether it be melodic ala Judas Priest and Iron Maiden or gutteral ala Kreator or Morbid Angel). Instead, nu-metal trades in the good things about the heavy metal genre for downtuned guitar flatulence that lacks power, whiny singing about juvenille subject matter, total lack of creativity, and a total lack of talent.
I'm glad in my early teens, when I had a pretty poor taste in music, that I didn't fully embrace the nu-metal genre. I'm glad I discovered REAL metal bands in my mid-late teens and as a result, burned all the bridges to what few nu-metal bands I liked.