I don't rate apps usually but Inkflow deserves it!
Have been looking a long time now for a decent app that could replace my 'old' paper notebook. However, most so-called notes apps are nothing more than text editors. I like to write something here and there on the paper, draw a little, add something there and circle something. Inkflow does it all and when I want to revise my notes later it's really easy.
Sure some things could be added, a document template for example, but for me its worth the money!