From an Article by Matthew Miller on ZDNet:
The Reader application not only gives you access to your Reader library though, it also offers another ebook reading experience on iOS devices. According to Sony, you will find the following features:
A natural, book-like reading experience
Intuitive navigation making use of the app as easy as the turn of a page
Access to your Reader library to read new purchases and old favorites
Personalized collections and library organization
Adjustable font size and contrast to customize your reading preferences
Create and edit bookmarks as you read
A choice between Day and Night reading modes
Read the Complete Review (via ZDNet)

