A recent report by the Pew Internet and American Life Project entitled The Rise of e-Reading details the profile of the e-reader and contrasts that profile with readers of printed books.
"The rise of e-books in American culture is part of a larger story about a shift from printed to digital material. Using a broader definition of e-content in a survey ending in December 2011, some 43% of Americans age 16 and older say they have either read an e-book in the past year or have read other long-form content such as magazines, journals, and news articles in digital format on an e-book reader, tablet computer, regular computer, or cell phone.
Those who have taken the plunge into reading e-books stand out in almost every way from other kinds of readers. Foremost, they are relatively avid readers of books in all formats: 88% of those who read e-books in the past 12 months also read printed books. Compared with other book readers, they read more books. They read more frequently for a host of reasons: for pleasure, for research, for current events, and for work or school. They are also more likely than others to have bought their most recent book, rather than borrowed it, and they are more likely than others to say they prefer to purchase books in general, often starting their search online." More
Here's an infographic representation of the report.