It was my favorite free app for reading college PDFs because of its cloud saving and underlining and drawing tools until I noticed that auto-save was failing a lot. Once I studied all day with the same PDF and when I left and came back everything I did was erased. I can't even review my old documents anymore because everything I wrote down was erased (even though I made sure to save it at the time). Because of this, I had to look for another app to study. I don't recommend it.