Jakob Nielsen’s Alertbox for March 14, 2011, “Can Hated Design Elements Be Made to Work?” states:
Usually, PDF files torment users on websites and intranets. Posting a sales brochure, annual shareholder report, or the HR manual online as a single, lumpy PDF file is a sure prescription for usability problems. Much better to convert the content into a navigable information space and rewrite it according to the guidelines for writing for the Web.
That said, PDF has its uses — they’re just not in the realm of interactive information access. When people want to download a report for later reference, PDF shines.
I like how Nielsen uses the phrase “interactive information access” to describe the web. Communication professionals, especially journalists, too often attempt to duplicate print media when planning a web site. Emphasizing the interactive aspect of the web is important when thinking about how to best inform and engage your web audience.