The app has all the usual features that a reader of this type should have. That is, you can change the font size, underline words or make annotations. It also has an automatic bookmarking system, so if you log out of the application, the page you were reading will be automatically archived.
Along with all this, Kobo has a bunch of social features that allow you to share your recommendations with other users from around the world, and even gain achievements/trophies/badges in the style of other social apps like foursquare or consoles like Xbox Live or PSN.
Kobo is one of the best ways to read on your iOS terminal. Furthermore, the application already has more than one and a half million free books that you can download and read without putting a dent in your pocket - a veritable treasure trove for all lovers of literature.