Adobe Acrobat Reader is a free application for reading and viewing PDF documents. It has a simple user interface wrapped around a standard explorer frame. Adobe Acrobat Reader supports several advanced features including multi view mode, page rotation, text copy, page snapshot and PDF printing.
Overall, Adobe Acrobat Reader is a great little application that is easy to use and simple to navigate. The downside is it only has some basic features and lacks more advanced functionality that comes with paid for products.