Sophie is Simple
When you first open Sophie you'll see the Library window, shown at left below. Books are opened by just clicking their title. The e-book window can show chapters in the left margin to move about easily.
Sophie is Useful
Passages can be selected and annotated in a Notebook. The Search tool lets you navigate among found passages quickly.
Sophie is Fun
Sophie's plug-in architecture lets developers using Runtime Revolution develop new tools for use in the program. While most of the tools included are merely useful, like the Text-to-Speech plug-in, they can be fun as well, like this Text Blender plug-in that makes text cut-ups: