I've heard "Rhapsody in Blue" by George Gershwin.  I find a few
passages in the piece mildly interesting, but musically and
structurally speaking, I don't "get it".  Maybe someday, I will.
This is not a criticism of the piece, only my observation.  
I do know this piece was immensely popular.

Cheers
Andy Taylor
Tempola Music Rolls