There are many sides to the debate about ebook readers (e-readers) compared to "real" books. Often the question of environmental impact centers around the fact that paper comes from trees therefore real books are bad. As in most such debates the reality is more complex.
Much of the impact of both types of books - and other products as well - occurs long before you even see them. Rare minerals and hazardous chemicals are used in the production of electronic devices as well as printers ink. An excellent article by Brian Palmer discussing this subject in depth in Slate Magazine is well worth reading.
Many discussions center around the "readability" factor. E-readers are said to be easier on your eyes than tablets like the iPad because they do not flicker. Some say curling up in bed with a computer of any kind is unnatural. Others prefer the physical connection with a nicely bound paper book as well as the ability to peruse a real library.
I believe that as desirable as real books, magazines and newspapers are for many, the battle is over almost before it has begun. Young people have grown up with electronic information sources of all types; the Internet has been used by the public for fifteen years. I'm confident most types of printed material will go the way of written correspondence, newsletters, technical journals, phone books, dictionaries, encyclopedias and reference materials of all kinds. These have disappeared with barely a whimper. The days of young children carrying thirty pounds of text books to school are numbered.