Pretty fun and nerve wracking level. I started playing this in the summer, and stopped because of nerve damage in my hand. I started playing this again about two weeks ago, where I would do 20-30 minute sessions once or twice a day to avoid injury. I spent about 43 hours before stopping in the summer, and about 6 more hours during the last 2 weeks. Altogether, this took me roughly 50 hours, but take that with a grain of salt.
(funny how this is only the 2nd hardest thing I've done today XD)