The trend is toward online Help and away from printed documentation. As user interfaces improve and become more standardized, the need for printed documentation decreases. It's been years since I have bought a software product from Microsoft with much more than 100 pages of printed documentation. I haven't missed it much. Since printed documentation is fairly expensive and difficult to modify quickly, you might want to follow this trend. Of course, providing printed documentation is a good idea in several cases:
Many tools on the market can help you create Help and printed documentation from the same content. You might not want to bother. Although this approach certainly promotes consistency, it scores poorly in helpfulness. Needing help, looking it up in the online Help, not finding the information you need, looking it up in the printed documentation, and finding exactly the same useless information is extremely annoying. What's the point?
TIP
Having exactly the same help online and in the printed documentation isn't helpful.