Unity 4 Beta contains many new important features (features) like:
completely new animation system "Mecanim".
DirectX 11 support
modern graphics for mobile devices
dynamic shadows for mobile games
the ability to create applications under Adobe Flash Player and Linux
advanced profile for mobile devices ')
Whether Unity3d will become a real engine for AAA games, I think time will tell. Linuxoids can rejoice over the past few months, this is not the first company in the industry looking towards this platform.