Key features (from the Messenger app page):
• Faster sharing: Select or take pictures and videos directly from the app and share easily. You can even send audio messages to your contacts.
• Easy search: Search through contacts and conversation threads to find exactly what you are looking for.
• Purposeful design: New, fluid, material design that is intuitive and delightful.
• More control: Ability to block SMS senders. No interruptions when you don’t want them!
• More features: audio messages, emoji support 😃, colored text threads, message archiving and more.
Messenger is supported on devices running Android™ 4.1, Jelly Bean, and above.