What Camille Paglia thinks of Lady Gaga can be found here: Lady Gaga and the death of sex | The Sunday Times. Some of it is good, although the way Paglia goes on about Madonna makes her almost seem a parody of herself.
As for me, I think she gets some of it right, but she misses the way Gaga is most like Madonna, and that is that both women have a way of reinventing themselves to stay firmly in the spotlight. Madonna was constantly shape shifting, and Lady Gaga seems to be doing the same. And if Gaga steals from Madonna, well, who did more stealing of images and sounds than Madonna herself?
As for Lady Gaga’s avant-garde approach to popular culture, I think it can be said to be just that: pop avant garde. Avant garde, if it can be said to exist at all in pop music, won’t come from mainstream performers like Lady Gaga. That doesn’t make her any less enjoyable and fun to watch. But musically she is fairly mainstream. Where she is avant garde is in her performances. More and more, pop music performances are lip synched dance extravaganzas. And if you accept pop music as being more or less than that, then Lady Gaga is avant garde. However, that is a pretty limited view of pop music, and so while I think Lady Gaga is entertaining, I will look for advances in pop music and pop culture coming for elsewhere.