First I have to say a few words about the building itself. It's probably one of the most hated ones in Paris, but I think it's a real masterpiece. The huge wall covered with piping was stunning, unbelievable, great.
I'm a big fan of modern art in general, but I had never seen art like that in my life! Picasso, Matisse, Klein, Miró, just name it. They are all there, all the masterpieces, from 'traditional' modern art from the beginning of the century to postmodern interactive art from 90's. Seeing them live was an amazing experience. Matisse's and Miró's works, for example, were nothing for me when I saw pictures and postcards - but now I concider them as one of my favourite artists.