As I have already said in other articles, an E-book is in Wikipedia’s words:

“the digital media equivalent of a conventional printed book. Such documents are either read on personal computers, or on dedicated hardware devices known as E-book devices or E-book readers”

E-books as such, have many advantages and also disadvantages. I find it interesting to mention the following pros:

Advantages

1. Text can be searched automatically, and cross-referenced using hyperlinks. This makes e-books an excellent choice of format for works that benefit from search and cross-reference capabilities, such as dictionaries, reference works, certain kinds of textbooks.

2. Less physical space is required to store e-books. Hundreds (or thousands) may be carried together on one device.

3. Readers who have difficulty reading conventional books can benefit from the adjustment of text size and font face. Text-to-speech software can be used to automatically convert e-books to spoken books. In addition, e-books may be read in low light or even total darkness, with a back-lit device.

4. An ebook doesn’t need to be held open like a paperback, so it can be much more comfortable to hold. It can also be set down and read hands-free.

5. Since there is only one page, there is not a problem with the text near the interior margin getting obscured or shadowed by the other page.

6. It costs nothing to replicate an e-book. Copies can be made instantly and in as great a quantity as desired.

7. Errors in texts may be easily and quickly corrected.

8. No environmental resources are consumed by e-book replication, cutting down on paper and ink production.

Now, I will focus my attention on disadvantages, which are the following:

Disadvantages

1. An e-book requires an electronic device to display it. Many e-book formats require special software to display them, which may not be freely available or compatible with a reader’s existing computing device. As an e-book is dependent on equipment to be read, it can be affected by faults in external hardware or software, such as hard disk drive failure.

2. Digital rights management techniques may be used to restrict what the user may do with an e-book. For instance, it may not be possible to transfer ownership of an e-book to another person, though such a transaction is common with physical books.

3. Unfortunately most e-book publishers do not warn their customers about the possible consequences of the Digital rights management scheme on their books.

4. With Digital rights management, it is more apt to consider the exchange of money for commodity to be a rental or lease rather than a purchase. The restricted book comes with a number of restrictions, and eventually access to the purchase can be removed by a number of different parties involved.

5. Current e-book devices still offer a lesser reading experience than physical books. Many readers prefer paper and print to a computer screen

6. From a publisher’s point of view, e-books can in some cases be hacked, or disseminated without approval from the author or publisher.

Sources: http://en.wikipedia.org/wiki/E-book