It's just another alternative, Alain. I have found an adage that one uses 10% of software's functionality 90% of the time; the remaining 90% of the available functionality is used little. Oversimplification? Maybe, but to pay the Canadians' the pri...
As a viewer it's fine, but when annotating the highlighting and comments are only for personal use -- they cannot be sent with the PDF doc. to others (or at least I could not do it...). For annotation, whether private or public, I still prefer the fr...