If you are familiar with Adobe Reader then you will have absolutely no trouble with FoxIt. The menus and navigation setup are very similar to Adobe Reader.
Here are some screenshots:

Also, FoxIt offers a Pro version, which allows you to edit PDFs, at a much lower price than Adobe charges (I believe Adobe charges $400+ while Foxit is only $99). The Bottom line, FoxIt PDF Viewer is faster, cheaper (its Free for the PDF Reader, and only $99 for the PDF Editor), and more reliable than Adobe Reader

You can download FoxIt PDF Viewer on FoxIts website here: http://www.foxitsoftware.com/pdf/reader_2/down_reader.htm