The stylus can write notes using the stock app, and you can click on the different pen sizes for small details or use a larger one for big fat lines. (goodereader.com)
Pressure sensitivity is incompatible with PDF files, so you will have to select the correct pen size for your needs. (goodereader.com)
In pen size alone the requirement was doubled even after they supposedly listened to the breeders. (tulsapetsmagazine.com)