Bye Bye Unity! I personally never liked you as a Desktop Manager.
In past recent months, there were rumors about Ubuntu’s Unity Desktop Manager which could be replaced by some Desktop Manager. And it happened officially in this October Release. We now have Mid Release of UBUNTU Version 17.10 ARTFUL AARDVARK.
Artful Aardvark now uses GNOME as its Default Desktop Manager. LightDM will provide you two GNOME session in Aardvark.
You can find the release information on Ubuntu’s Official Release page. But currently (15th of October) The Ubuntu Wiki is not updated. So in order to download the iso what you can do is browse to your nearby ISO Mirror Provider. Here at Nepal Nepal Telecom provides us with the ISO of every Ubuntu Releases. So Ubuntu users from Nepal can download Artful Aardvark from the link provided below:
This is not the only way to upgrade your Ubuntu Distribution. You can also update it from your Settings by Checking for Updates. Update Menu provides you the Official OS Updates from where you can upgrade to Artful Aardvark.