However, from the get go I had trouble figuring out what it would be good for. A friend convinced me that it'd be perfect for emergency situations, such as hurricanes, since one SMS could be used to notify a lot of people, and I consequently signed up. I've given it a try, but I have been unable to make it work for me. I've pondered why and discussed this with people, and here are my conclusions so far.
It Replicates Existing Functionality
I used to keep track of what friends are doing on LiveJournal. They'd post their travels, plans for parties, reviews of books they'd read, shared nifty links and so forth. This works quite well, in my view, and is still my primary social channel, although it is obvious that a lot of my friends have migrated away from it.
LiveJournal, BlogSpot, Myspace (yuck!), Flickr and Facebook, among others, allow for updates via SMS, MMS or mobile browsers. If I see something interesting while I'm out and about, and I can even upload pictures and video if I so desire.
Artists, news outlets, and other similar content creators have RSS and Atom feeds. I can subscribe to them on LJ, on my mobile phone, with Outlook, with Google... Any number of ways I can conveniently see a headline-format update from any number of sources I want.
It Annoys Me
I get perhaps one social SMS every week or so, including "I'm coming home, let's move cars"-type messages. Those that I do get I generally don't mind. Things such as planning weekday lunches, movies and whatnot happens via LJ, email or AIM. The majority of SMS messages I get are work-related pages: something broke. Consequently, whenever I get one, I have to look at it as soon as possible; when driving, eating, in the movies, in class, doesn't matter. Pull over, excuse myself, check the phone with a mental preparation for having to drop what I'm doing and find a computer or drive to work. The result of this is that I do not want to stop a conversation or slip out of a meeting or make a professor mad to find out that my friend is having a delicious sandwich. Which leads me to...
No Content Separation
Some of my friends plan social activities through Twitter. If you do not check your SMS, you don't know they're going to the movies and want company, or want to do lunch. I still don't want to enable SMS notifications, though, because most of the messages would still be things I am not really interested in being alerted to -- and there's no way to filter this.
Whenever people post links on Twitter (and now photos and videos, which really is replication of perfectly good existing functionality) they tend to use a URL shortening -- and obfuscation -- service. Hence, if I follow the links, I end up seeing every old Internet Meme a dozen times, since there's no way to tell what you're clicking on. The security folly of this is left as an exercise for the reader.
There's also no proper way to group my own updates. I don't want the world to know what I'm up to, so I have to make my feed private. I now can not link it to Facebook, LJ, or any RSS aggregator. I also cannot select which people see which posts, unlike most other social media; I have many friends, some of which might be offended by sexual content, for example -- and there are things I want to share with some people but not others.
If all my friends were on Twitter and used SMS notifications, it would be an interesting way to alert everyone with one message for really important stuff. As is, for my use it does nothing (as I can't know who will get a tweet and who will not) that my existing social networking services do not already do, and the existing services do everything better.