Up until now, Snapchat only allowed users to look at an image once before it was deleted, but users can now choose one particular message every 24 hours to replay. You can only use the feature once every 24 hours, so you'll have to be selective over which message is actually worth the replay.
Those who send messages may also have to be a little more considerate over what they send. Some users have taken advantage of Snapchat's messages and their short life span to send more intimate messages. But those could be shown off to more people thanks to the replay feature, or the person receiving the message could get a camera to screencap the message without alerting the sender. If you're sending a personal Snapchat message, assume that it will be seen by more than the person you're sending it to.
In less ground-breaking news, users can also apply "Smart Filters" to their images. These overlay messages with info such as current weather, time, or the speed they're travelling. There are also new visual filters and fonts to make messages more appealing or eye-catching.
Snapchat is rolling out the iOS and Android update Monday.