Make notes (and more...) on PDF's

I often need to review documents sent to me in PDF format. Since I own a Tablet-PC, not to take advantage of the calligraphic interface for that is not an option. For years I have used the Adobe Acrobat Professional v6.0 for that purpose. However, the version 6.0 was not clearly designed to be used with a pen and we have no license for newer versions (currently 9.0). Thus, I tried a few other tools and concluded that, in my opinion, the Grahl PDF Annotator is the best option to make notes on PDF documents.