I don't know about the "extremely" difficult part but certainly it is more difficult and you need to be realistic in your expectations. I learned piano when I was a kid, rather I was forced to by my parents, never really enjoyed it and was mainly parroting than really learning. Now I am trying to learn electric guitar and I am much more interested in learning about music theory, reading music, and how to practice effectively, etc than I ever was as a kid. The first piece my instructor gave me was "Ode to Joy" and I thought I would never learn to play it, but I got through it and then another piece and at some point something "clicked" and my ability to play shot up dramatically - not anywhere near what even a mediocre guitarist can play but much beyond where I was even a short time ago, so I can directly relate to the experience of this article. You may not be aware of the progress you're are actually making because it doesn't always happen in a nice smooth curve. Keep plugging away, you'll get there .