I'd done the tourist thing a few times since 1991 and always came away a bit bleeeerrrgh. But I went to the Summer Solstice a few years ago and got inside the stones. . (or inside the circle, should I say), and yea, it was superb.
I've been back inside a few times since, at the winter solstice. It's even better then.
I think it's too famous to be 'cool' in a way, and I think some people think it's too new to be proper megarak stuff, but I think it's something very special. Being inside you certainly get that 'wow' factor.