He is very underrated as an American composer because his works are so complicated. I enjoy listening to small doses of his work when I can find it, I prefer Ligetti or Schnittke but it is good stuff and he led an interesting life, he was at Princeton when Einstein was there.
http://laurakarpman.com/new/index.ph...d=70&Itemid=58
check it out if you like to experience different things.