Found this on the App store today and noticed it was cheaper than normal!
It is currently 40% off for being 'Apple Editors' Choice. (now $2.99 from $4.99)
Very useful app for making notes in general and noting pdfs, which can be hard on an iPad! A few of my teachers use this to mark my work and some of my friends have it now too. It also has a solid 4-4.5 star rating.
Welcome to Notability, the best-selling note-taking app on iPad, iPhone and iPod touch. Notability is so powerful that it will transform how you work: sketch ideas, annotate documents, sign contracts, complete worksheets, keep a journal, jot travel notes, teach a class, make a presentation and much more. With iCloud support, your notes stay up to date on all your devices!
This is a great app, I have been using it for over a year now and it is probably one of my best purchases I have made on the app store. Good deal!!