With CDF's inclusion in pentaho, the user base has increased a lot. And I'm absolutely sure that the vast majority of the users that download Pentaho have no idea of what they can do with it.
Looking back to 1 or 2 years ago the improvements have been huge; We can now develop Pentaho dashboards in 1/10th of the time, being able to focus on content, and not in technology.
Still, I have to admit that it's still a steep learning curve to a new users.
We are working on a set of samples/tutorials to make it easier for new users to understand how it works - from simple inputs to sparklines in dashboards.
Our goal is have it ready in the next month; Not sure how we'll distribute it - probably with webclasses or something like that - but we'll decide it when it's finished.
In the meanwhile, here's a screenshot of the work in progress, where tutorial itself is a CDF dashboard