I was sceptical at first, but now I can see the advantages of text messaging.  I don't think it's useful when you have 9 buttons that represent 26 letters, like on a regular cell phone.  But ever since I got a Treo 650, it's been worthwhile because there's a full "qwerty" keyboard.  I still don't pay for unlimited text messaging, because I don't use it enough to justify the cost.  But I think the idea is great.  Instead of calling a person and going through the whole "Hey, how are you?  I'm fine" nonsense, you can get straight to the point.  You just say what you're trying to say and you're done.  Another benefit is that text messages are plain text, so people most likely won't forward you junk.  And the good part about typing things on a small keyboard is that it's difficult, so most people probably won't text message unless it's relatively important.

So in the end, ideal text messaging is (1) personal communication in (2) plain text that's (3) to the point and that's (4) easily accessible anywhere.