I grade my students' papers every day with this app. The easy annotation and highlighting are amazing. It's much cleaner than simply scribbling on the paper. Now my students will actually read my feedback for them.
The program works great. It does everything I want it to do in terms of making all kinds of notes on the PDF file with highlighters, text notes, freehand drawings and arrows.
I use this app all the time. It is intuitive and easy to use. I can manipulate, add and take away pages with ease. I don't know how I would cope without it.