I have been remiss in linking to this discussion on Acronym about meeting formats. I kept holding off in hopes of having something brilliant to add, but people over there seem to have it covered pretty well. Basically, it's about whether the new drive toward interactivity is a good thing or not.
For the most part, I like more interactive sessions (which is a little strange for a hard-core introvert, but there it is). But I also understand the "I paid to hear an expert, not some other Joe Shmoe" objection. As several people pointed out, I think the key is to let people know exactly what to expect, so those who like learning more hands-on can do so, and those who prefer a more passive approach can have their lectures, too. We all learn differently--the key thing is to give everyone at least a few sessions that cater to their preferred learning style.