You can write your notes normally, using your keyboard, or you can use your mouse or graphics tablet for note taking. You can customize options such as the color of the outline and the structure of the text and drawings in layers.
More interesting tools that are available include an eraser, which is essential when drawing, and a yellow highlighter, which is very useful for taking notes.
Unfortunately, the program is still in an early development stage and is quite unstable, so it is advisable to save your progress often.
Xournal is a very interesting tool, although its stability problems prevent it from being especially recommended.