I see more and more teenagers using Snapchat, and if you're a parent of a teenager with a smartphone, you need to be on the lookout for it. Snapchat is an app that can be used as a texting or messaging service. However, it has its pitaflls.
First and foremost, it uses cellular data. Years ago, Blackberry boasted that their BBM service was a cross-carrier app, so those with unlimited data and limited text could message each other witout worries that they would exceed their meager messaging bundles. Now the pendulum has swung the other way: we have unlimited messaging and limited data plans, so the need for a multiplatofrm, multicarrier messaging isn't as great. Texting through Snapchat shouldn't use much data, but the operative word here is "shouldn't." A few coworkers of mine burned through over 100 MB of data within a few hours of sending various pictures and texts via Snapchat. That's a tenth of a gigabyte. So if a few grown adults can burn a tenth of a gigablyte between the two of them, imagine what your teenager can do messaging multiple friends hundreds of times a day over the course of a month. (Hint: it adds up fast). If you experience a sudden surge of data usage that nobody on the family plan is fessing up to, look for Snapchat on your kids' phones.
Second, the big draw to Snapchat is that the messages are self-destructing. Send a message and a few seconds after the recipient opens it, it deletes itself. I am not really concerned about kids using Snapchat to circumvent parental supervision, that dance has been happening as long as parents have had teenagers. So I'm going to leave you as a parent to discern what level of trust and verification to hold your children to.
What bothers me is that teenagers already have a false sense of invincibility. Giving them a smartphone app that allows for rapidly self-deleting messages feeds into that just a little too much. It says right on the app description that while messages are deleted from your phone and Snapchat's server after a few seconds, a screen capture can preserve that message for posterity. Plus, one has to wonder in this day and age if what gets deleted really gets deleted. Do you really want your children learning that lesson the hard way? The first high-profile case that the evidence has been passed along via Snapchat will reveal how truly deleted (or not) those messages are. I suspect you don't want your children to be the guinea pigs here either.
Bottom line is that if my kids were old enough to have their own phones, I'd prefer they not use apps like Snapchat. If your kids already have it on their phones, it's up to you as a parent to decide what battles you want to fight, but at least you should know what the app is and what it can do. If you need a seperate app for messaging over data or wifi, say from an iPod touch to an Android, or for international travel, I recommend What'sApp Messenger.