You're right - people get confused between a UI's learnability vs it's usability. Just because you need to ramp up on something initially doesn't mean it's hard to use over time.

Plus a new feature can get lost or ignored by people already familiar with an existing interface, so it needs it's own little mini walkthrough just so it'll get noticed. Here's an example of Facebook's mini popups focused on a single new feature:

http://cl.ly/image/3a3c1z2f0j21

I've built wizards of various kinds over the years and I call them "training wheels". The trick is to make it so they can start pedaling on their own relatively quickly, rather than using it as a catch-all where you dump every possible use case.