You have to pardon me. By unified i meant mobile. I am not sure about state of desktop. I from time to time use mac app with no issues but Signal in my eyes is sms alternative.
It works OK, but it's no iMessage.
I miss using Adium as my native Mac chat client for everything, alas AIM is dead and Google killed their Jabber interoperation.
I'm not a heavy multimedia user, but Signal's Mac and iOS apps have been working wonderfully well for me and my friends.