A study of people reading long-form text on tablets finds higher reading speeds than in the past, but they're still slower than reading print.
Enjoyment level was comparable with printed books. I find this to be true in my experience:
Users felt that reading the printed book was more relaxing than using electronic devices.
I love technology and reading on the iPhone and Kindle, but I also love printed books. I struggle with which format to buy every time. I should avoid the dilemma and just get a library card.