As they say, your mileage may vary, but personally I’m a fan of roleplaying PDF products. I can save money and space, more easily explore new games, unobtrusively read game books at the office (oops!), and get early access to materials later available in print. A good example is the recently released Six-Shooters & Spaceships sourcebook for Serenity. It details 26 new ships, as well as robots, guns, and other gear, and and the PDF version is available now. On the other hand, with low production costs nearly eliminating the barriers for new products, you’ll also see alot of this.