There are not difficult pieces in the piano. Or all the pieces are
difficult.  When you have to carry out some arrangement like in the
Goldberg Variations of Bach or Albeniz's Iberia can it take more time.
La Campanella is not a more difficult study that anyone of Chopin.

For example, works easy as those of my edition of Felix Maximo Lopez
they are extremely difficult of playing well.

Alberto Cobo
www.superopera.com