If you have little ones and you are looking for the best E-Book app available, go download "The Monster at the End of this Book". I have yet to come across a child who doesn't just love this book. The E-Book app allows the reader to interact with the book as well. The child can untie the knots, break the brick wall, etc. Grover's voice is a magical addition to the book.
Now, please don't expect to find any miraculous aspects within the app itself. The key to remember is that it simply a great book! No matter how good an app is, the content will always remain the most important aspect.
Additionally, you can't get this book in print for .99 cents. This is an immediate buy in my opinion!