I just downloaded the new Beta2 of Ubuntu Gnome 16.04. Its a nice desktop with so many improvements and this is the Long Term Support Ubuntu version. I install this Ubuntu Gnome 16.04 on my VirtualBox for testing. The installation went well and first of all, I will install VirtualBox Guest Additions on it.
Installing Guest Additions on Ubuntu Gnome 16.04 is very easy. Once log in, click Device | Insert Guest Additions CD Image from VirtualBox menu. Ubuntu Gnome 16.04 will automatically detect the file and provide a direct installation option as follow
Click Run and enter your root password
Make sure there are no errors and next, log out and re log in. Now Ubuntu 16.04 should be more faster and have better resolution.