Print 2 Phone is indeed a PDF viewer, but is also a lot more. There are several features that make Print 2 Phone unique among other viewers. The most notable is the ability to "print" the documents to your iPhone, iPad and iPod touch.
Print 2 Phone's purpose is to be the easiest way to get your documents on your phone. There's no need for cables, everything is done over the air. You don't have to deal with PDF files. No matter what kind of document you have, Print 2 Phone will convert it to PDF as long as it is printable. It also has a very fast and efficient PDF rendering engine. And after all if you still prefer another PDF viewer, you can still use the "printing" feature and Print 2 Phone will give you the option to open your documents in any other application that supports PDF.