This museum has all of the modern mischief makers and envelope pushers that you learn about in art…read morehistory classes--Miro, Duchamp, Kadinsky, Klein, Klee, etc--plus their lesser known peers and contemporary artists. It's exciting to be around so much creativity and spark.
The building itself is a draw, and you can enjoy the nearby fountain filled with moving statues and take the famous elevator all the way to the top for free--the view is the best, and I prefer it more than the view from the Eiffel Tower! There is also a notable bookstore filled with art folios and a wall of postcards, accessible without tickets.
If you enter the paid floors, expect to be wowed for at least 2-3 hours.