sadly the proles have started getting a hold of twitter, and naturally it's getting dumbed down and oversaturated.
I used to hate twitter forever, then I relented and realized it can serve a purpose, now I hate it again, so I think I can offer some good insight.
First - twitter came before facebook (at least the feature of twitter that we are discussing) So facebook in that regard is like twitter.
It's mainly used for mass communication with friends. It's useful if you want to send something out to 15 friends to meet you at a bar or something. Also I think because it's not loaded with other features it's more streamlined and efficent than facebook. Also not sure if facebook texts your phone?
Sadly fucking idiots are using it cause it's the in thing now and they all want to tell us that they just saw a bird fly by.
I think the reason it's exploded so much is because up until recently, web novices couldn't really have a webpage without at least some technical know-how. Before web 2.0 (ugh sorry for using the term) People would build and code their pages from scratch. Then blogs blew the fuck up and now it was easier for some to just install a blog template like wordpress and go from there, but you still needed to have some knowledge. Twitter is taking it to the next level, now everyone can sign up, have an online profile, and type daily updates.
What it really boils down to is bandwagon idiots thinking that texting a webpage is a revolution.