I do not use Twitter, so my reactions are colored by that. To my eye, the tweets excel at coordinating meetings, dealing with varying sorts of live information, and quick-capsule synopses of talks. (Catherine Grant's summaries are particularly impressive in scope.) The latter seems like a useful in-between information between title and abstract and helps conference-goers get a sense of panels they are not able to attend.
Maybe because I don't write in such short-form entries, I'm especially impressed when more substantial dialogue manages to happen. And it does happen. Perhaps my favorite insight comes from Jason Mittell: "I think everyone in the field thinks that their approach is marginal, other approaches are hegemonic." These back-and-forth comments perform useful traces of disciplinary conversation. Of course, I agree with Rick Prelinger, that the coverage is "skewed and asymmetric." New media, TV studies, and media industries panels got much more discussion than less contemporary-oriented subfields, and this expresses the varying social media usage in the field.
Moreover, the substantive conversations were about the process of scholarship, about digital humanities, and about Twitter itself. I come away from the conference thinking that Twitter is less useful in deliberating about our object of study than in aiding a meta-deliberation about what a disciplinary sphere should be. My take is that the latter project will actually be aided by more of the former.