I think every band with some measure of popularity are to varying extents, overrated. The Beatles are a good example. Their longevity as artists and the evolution of their work are traits to be praised, which makes them great, but I'd say their cultural relevance for the 60's, as well as their influence in other genres, is what makes them rated as greater. I find that those who love classic Britpop (i.e. The Stone Roses, Oasis) are more likely to find more common ground with liking The Beatles than others who find other styles of music their cup of tea.
I'll admit that I liked Green Day and Offspring when I was 12-13, back when Dookie and Smash came out. Looking back on it, both bands were/are no more than a fad to me now. That might sound harsh, but their older works became annoying to say the least, which makes their newer stuff not worth delving into, in my book.
Personally, I never cared much for Tool or A Perfect Circle. I roll my eyes at Tool fans who think that folks who don't like their music lack musical intelligence, but for some reason or other, I can't get myself to like their music. Quite simple really. I like my music with a faster pace, more riffs, more solos, and well, meaner.