Pro Messages have user-defined lifespan
Messages can have a lifespan between 3 seconds and 6 days. Received messages arrive locked. Once they are opened by the recipient, a timer starts counting down until the message is deleted. Of course, the recipient can still copy them or take a screenshot.
Pro By default, doesn't allow taking screenshots
Wickr disables the screenshot functionality altogether when the app is open. However, there are ways to circumvent this, as if the user has a rooted phone and has installed apps to overide this block or if a screenshot is taken via some apps that project the screen to a PC.
Pro Can find other users securely
Instead of using usernames, emails or phone numbers to find other users, Wickr uses hashes derived from phone numbers or email addresses (this applies to the find friends functionality only). Hashes are the result of a one-way cryptographic function, meaning it's purposefully difficult to reconstruct original data (phone numbers and email addresses in this case) from them. For Wickr, hashes are generated on the client's side so that no personal information is ever sent to the Wickr servers. The app finds people on your contact list that also use Wickr by comparing the hashes that get generated from contacts and comparing them to the hashes that are stored on Wickr servers.
Con Small user base
Wickr claims that one million users have downloaded the app with no information on how many active users they have. But even if every person that has downloaded the app is an active user, the userbase is really small compared to apps like WhatsApp that boast about hundreds of millions of active users.