I tried it for about 15 minutes. Was checking it out to see if i should let my daughter have an account. Nope. Not comfortable with other having ability to send her inappropriate things that disappear in a short while. Also, the UI is horrible and not at all intuitive. She was sad but she will live.
Ah BBM even does that too, where you can set them to disappear, it actually saves on cookies and cache, but regardless people generally just add their friends on there, it is not about non-friends like Twitter is. It's more about messaging with friends, not strangers.
That said, people use it to also follow singers and celebs because you can get stuff they post before any media or news sees it. I like how they give some news and global events in Snapchat but they do it in a fun way. I bet if it wasn't for SC most younger peeps wouldn't even know there was an election on.