I also use it to keep in touch with my wife when we in different places, as it’s easy to use via SMS on a cellphone. It’s the brevity that’s good too. Not a huge amount of options – just 140 characters of text (which can be a URL) and away you go.
Perhaps it sounds a pointless little app. What’s wrong with a phone call, or just a text message. Well, nothing perhaps, but that forced brevity is good compared to a phone call that is meant to be short, but goes on for a half hour or more; twittering is easier if you’re at a PC, than finding the cellphone and using the keypad, even if you’ve got a latest generation smartphone.
I would suggest you try it out if you haven’t. You might find it’s more useful than you imagined.