I remember finding the whole generations concept fascinating when I first heard about it, but I think this quote from the Wikipedia article sums up my misgiving

I remember finding the whole generations concept fascinating when I first heard about it, but I think this quote from the Wikipedia article sums up my misgivings about the concept : "Britney Spears is seen publicly as the female pop icon of Generation Y[19][20][21][22], due to her enormous music career success and pop culture impact during the late 1990s to early 2000s. Eminem is also a huge voice for the Generation Y. His album "The Marshall Mathers LP" has affected many of the youths in that generation." This is about as useful as saying "the average human has one testicle". I imagine the intersection of "people who like Britney Spears" and "people who like Eminem" is fairly small, yet you hear a lot of this kind of thing, where it's assumed that most Gen Y-ers were involved in all the trends of the 90s and 00s. I can understand that there's certain cases where saying "x% of people born in the 1980s like y, compared to only z% born in the 1970s" can be informative. What doesn't work is when the media starts trying to amalgamate all the trends into a narcissistic, apathetic, social-network-using, ritalin-popping, blogging, twittering, hyperactive, Pokemon-playing, tech-savvy, lazy, childish, ADHD-suffering hip-hop listening, emo self-centred archetype.