The magazine owes its success to having a broader range of interests than its closest competitors The Source and XXL which focus more narrowly on rap music or the rock & pop-centric Rolling Stone and Spin. It also differs from the more staid Essence, Ebony or Jet publications by attracting younger readers of many ethnicities.
It was essentially the black version of Rolling Stone, and its readership grew broader as hip hop became pop music. (Kind of fitting that their last issue had Eminem on the cover). But Vibe hasn't been doing well for a while now; in February, the magazine cut its circulation and frequency, and salaries. Now the music industry is crumbling, and the magazine industry is crumbling, and the music magazine industry is really crumbling."
VIBE, though not always great, was truly one of the good guys.