It provides following advanced User Interface features:

1. Excellent search features have been included.
2. Quick navigation or quickly navigates.
3. Pinch zooms in on text for a closer view.
4. Navigate through pages just by tapping or by using document outline.
5. Multi-touch pinch-to-zoom.
6. Double tap to fit to screen width(great for tablets!).
7. Support for encrypted/password protected files.

It becomes handy as it keeps a track of your favorite pages and allow you to bookmark them.