I consider John Adams to be a post-minimalist composer. His early music, such as Phrygian Gates, was clearly influenced by Reich, Terry Riley and Philip Glass but in general he seems more like a neo-romantic with some minimalist tendancies. Harmonielehre has some development and climaxes you'd expect in a romantic symphony. I find Adams to be a much more sophisticated composer than Glass. For example, where Glass might write an extended passage with 16th notes, Adams would write a passage with offset rhtyhms that result in a 16th note feel. I just find Adams to be more skilled and dynamic and also fit within a tradition while using minimalism as a technique rather than a goal. Overall, I find his music to be very good. I love Nixon in China. It is a very effective piece and probably one of the great American operas. Is he a genius? That's hard to say, but I would certainly describe him as an effective, intelligent, communicative, relevant contemporary composer.