I've had a Twitter account for about a year and never tweeted once until last week, so I am definitely a newcomer to the Twitterverse. When I started my Twitter account my intent was to use it as a professional development tool. I never followed through on that because of the overwhelming sense of chaos I felt as I looked at my feed. There's just so much STUFF piling in all the time. It seemed impossible to keep up with it all. And to be honest, I was (and probably still am) put off by some of the linguistic doomsday prophets who warn of the dangers of reducing discourse to 140-character spurts.
After using Twitter a little more concertedly this week, I'm still overwhelmed by the inexorable march of tweets streaming across my feed. However, I've seen some of the advantages of the 140-character limit--for one thing, it's a lot harder for people to dominate conversations the way they can on Facebook. You'll never see anyone write TLDR in response to a tweet. I've also seen what Justin Lanier (writing on the MTBoS blog linked above) calls the "funny combo of synchronous and asynchronous communication" that happens on Twitter.
Probably the best part of Twitter (and weirdest, for me) is the ability to follow and even tweet at people whose work you admire. There are blogs I've read for a while written by gurus in my field, and I can send a tweet their way just like that! Nothing stops me! I don't have to track down an email address and carefully craft an introductory letter hoping that I can disguise my inner fanboy enough to sound like a competent professional, all so I can maybe hear back from someone I look up to. I can just tweet them! And on their side of things, they don't have to worry about 1,000-word emails from fans. One hundred and forty characters, max.
In summary, I'll continue using Twitter, but I don't know if it will be a go-to tool for me.