Here's a confession: I've done no more than dip my toe into Twitter. I know it's where the conversation is, I know it's the latest toy loved by celebrities and social media mavens. I know it's where news breaks and gets discussed. I know it's a great example of the mobile internet.
I also recognise (and this is best of all) that it's easier to get into than blogging, so a new generation has skipped blogging and become enthused by real-time conversations on Twitter. (Consider the irony: blogging, like email, is considered 'too slow' by Generation Y whose members grew up on instant messaging and mobile phone text messages.)
But even so. I'm not fashion-conscious and I'm keen to keep the noise down and cut through the clutter. Besides, I don't currently have any clients so the need to be actively engaged is lessened. If anything, I've moved more of my reading in the direction of good old-fashioned books in the past year. There's a tension here and I'm pulling against the trend.
But there's something else, a concern about the trade off between speed and substance. Stuart Bruce points to a post by Robert Scoble (in turn quoting Forrest Research analyst Jeremiah Owyang):
"The other night Jeremiah Owyang told me that thought leaders should avoid spending a lot of time in Twitter or FriendFeed because that time will be mostly wasted. If you want to reach normal people, he argued, they know how to use Google. And if you want to get into Google the best device — by far — is a blog."
So it's OK for me to come out as a Twitter refusenik. See how I'm ahead of the curve?
PR Studies 
Actually recent studies show that Gen Y might not like Twitter or use it nearly as much as reported in the media. In fact, Twitter has become an older generation phenomenon with almost 78% of the site’s traffic coming from those older than Gen Y. Additionally, most of the people who sign up for the site become inactive after only a month, and only about 10% of the users generate about 90% of the content (which is much higher than on other social networking sites). Here is one article that I found on Gen Y usage (http://news.cnet.com/8301-17939_109-10265060-2.html). There is another one on the Harvard Business Review, but I couldn’t find it at this time.
Also, I think the limitation with Twitter will always be the small amount of content that can be transcribed. There is no way to put forth interesting arguments because the system does not allow you to use more than 140 characters. My personal belief is that unless Twitter can develop a hybrid model that includes larger pieces, it will only become a sign post site which directs traffic to various blog posts, articles, thoughts, and web pages.
Thank you Richard, you’ve just given me a handful of reasons for continuing not to get round to sorting out a Twitter account.