Apart from the redesign, the key feature is the phone number integration, which will bring it in line with Whatsapp IM feature as The Verge reports:
While Facebook won’t let you text a phone number from Messenger, the company plans to use phone numbers in a new way: to identify its users, just like in WhatsApp. Upon opening Messenger for the first time, it will ask you to provide your phone number.
Then, the app can match you with people whose numbers you have, but whom you aren’t Facebook friends with. Facebook guarantees your messages will reach somebody’s inbox if you have their phone number.Profile images will now be presented in a circle while left and right swipe gestures will be used. The contacts names will have a blue badge which will help users to identify whether a chat is conducted from the web or the Messenger app. The Active tab will include all those chatting from the web.
shows that there are two settings for those who can look up a user’s phone number and email. First – a user can control who looks up the profile using the phone number. Second – telling who can use the email address to look up the profile.
If you choose to use Messenger, you may be asked to adjust the setting for ‘Who can look you up by the phone number you provided?’ to Public so people who already have your phone number can reach you on Messenger.The new features are likely to increase the popularity of Messenger.
As you wait for the update, download the app for free from the App Store if you don’t have it already.