I do enjoy the #ff tradition if it's done properly (not that I have not been guilty occasionally of improper tweets in my day). When someone tweets something like "#ff to @HJarche because he shares insight into collaborative learning" or something like that, I do often find new people to connect with.

Conversely, it's not very helpful to see just #ff followed by a slew of twitter handles, and I can understand why that practice might be grating to people.