Spotlight: SMS Encryption is a no-frills, AES-encrypted secure messenger
As for the app itself, it manages to wrap its functionality in a friendly, colorful interface that doesn't behave itself like it jumped out of an obscure 90s 'hackers' movie. It also uses different keys for the respective secret messages, and it lets you create real-time private chats with another person. It's like BBM Lite.
SMS Encryption has some limitations, though. For starters, it can't be set as your default Android SMS app. It also doesn't allow you to delete messages for some reason, and it doesn't do MMS. It is customizable to a degree, still, letting you sort the conversations list by date, exclude messages sent by an unknown person, and request delivery reports.
It's like BBM Lite.
Although SMS Encryption is still in its infancy and it is a little basic as an app, it already covers enough territory to provide the needed functionality to those looking for the simplest of private messengers. You probably won't see stickers and credit packs hit this one in its lifetime either. So if you like how SMS Encryption sounds, get it from Google Play for free.