What makes Snapchat so different is that the messages self-destruct shortly after they are opened. Once a Snap is sent, that's it--you won't be able to see it again. And after the recipient has opened the Snap, he or she only has a few seconds to look at it before it disappears. The sender designates the Snap's lifespan by setting a timer. You can see a log of all past Snaps, but you won't be able to see the contents.
One important setting to make note of is "Who can send me snaps." I toggled this from Everyone to My Friends, because the thought of getting a random photo message from a stranger isn't my idea of a good time.
While none of these messaging services can truly replace Messages, the experience of sending platform-to-platform messages excels with WhatsApp. Chat logs are easy to view and manage, the checkmarks next to read messages provide a peace of mind, and the variety of multimedia message types is a welcome sight. The problem with these messaging services is that they're only good based on the number of people who use them--while I can use WhatsApp to message with some of my contacts, I cannot use it as my primary platform, and will never be able to under Apple's current restrictions.
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