Concerning the usefulness of Twitter:
I too tried and didn't like Twitter several years ago, and I thought it was mostly useless. However, once I found myself in the midst of a terrible natural disaster (Japanese earthquake), an expat with rudimentary knowledge of the language, I followed several foreign journalists (living in Japan) on Twitter and was receiving news 4-6 hours before I would see it on TV. More skeptical than the Japanese media but not as frantic as foreign media. The information stream was so useful I decided to give Twitter another go, and I'm glad I did.
In the last year there has been plenty of evidence of Twitter's usefulness during hot situations, and I find myself using it more during mundane times in order to keep those twitter skills sharp for the more hectic events (god forbid).