Here's how you can install Unity 7.2 in Arch Linux. This will let you use Ubuntu's Unity desktop environment on your Arch Linux system.
1. Open a terminal window.
2. Type in the following command then hit Enter.
sudo vim /etc/pacman.conf
3. Paste in this text.
SigLevel = Optional TrustAll
Server = http://mooos.org/repos/moo/$arch
4. Type in the following commands then hit Enter after each.
sudo pacman -S unity
According to Linux G:
I will show you how to install Unity 7.2 on Arch Linux. Unity on Arch Linux has the same functionalities as it has on Ubuntu, all elements (AppMenu, applets, etc) working properly.More at Linux G
Additional resources for Arch Linux