I've been into Anthrax since '87. My first purchase was I'm the Man EP after finding it in a bargain bin and saying What the Hell? I liked it enough to buy Among the Living, and not too long afterwards State of Euphoria came out, which I bought the day it came out. They were okay, never my favorites, maybe cracking the top ten. I liked their not-too-serious attitude, something that made them more fun than the other thrash bands. Never really cared that much for Joey's voice, thought it was the weak part of the band, especially on high notes where he'd occasionally crack or just sound off-key, it would almost make me cringe.
I like the direction the band has taken since John joined. I think John's voice suits metal music more, and I think the music itself has been superior. I think the production has really tightened up, and while there may not be as many "thrash riffs", to me the overall sound is heavier than before. They went from being in the top ten to unquestionably being my favorite band, with SOWN, Volume 8, and Stomp being easily the best albums of the 90's, and SOWN and Volume 8 being two of my favorite all-time albums.
So in answer to the original post, I'm certainly consider myself "old school" in terms of how long I've been into Anthrax, as well as my other tastes in metal (which still mainly revolve around acts that originated in the late 70's early 80's, or the rare newer band that emulates that sound), but I still consider Anthrax's newer (ie. John) stuff to be vastly superior. If you want to call me a "newbie" for that, so be it (although I might headbutt you for it the next time I get drunk
)