I have never tried Twitter. As soon as I heard about the max chars it sounded like a bunch of bumper sticker arguments were inevitable. Not even sound bites, but sound bits. Maybe if I had a reason to use it I would change my mind. I tend to be too skeptical of new things. Which reminds me, Mouser I do like the new format on here.
What it is supposed to be for is little bits of information that are not worthy of a standard blog format or article on a site. Standard articles have a certain format that they use in order to increase surface area- if you want to say that Harrison Ford fell on the set of the new Star Wars movie, if you reported it on CNN.com or EW.com, you'd have a lot of fluff and filler. In a micro blogging format, you just tweet the relevant headline. Or you can tweet individual comments that are concise and to the point.
They first bastardized that with links to the full article- so as to redirect traffic to their sites. Then they started with multiple tweets, or images. And twitter became this site where people just spewed things, with no real difference from other sites- other than the hypothetical 140 character limit.