With the new release of Skype for Business 2015 the following features were added.
New look and feel,
Bringing the familiar “Skype Interface” to the enterprise client.
Call via Work for desk phones
Call from Skype for Business using your desk phone for audio, which makes integration easier with legacy PBX:s
Integration with the Skype directory,
A highly requested feature. Gives the ability to search the consumer Skype directory, and also communicate with users that haven’t merged their Skype ID with their Microsoft account.
The Call Monitor will always float over other applications if you change focus on your screen.
Quick access to call controls
Controlling calls was a couple of clicks away in Lync 2013, in Skype for Business these controls are always just one click away.