This texture pack was created for SantaUI. It will work without SantaUI, but it's not a complete re-texturing of the UI and will not look as good without it installed. You can download SantaUI here!
** Read: How to install **
This is not an addon, but a texture pack! To install it, unzip the folders in your "World of Warcraft/Interface" folder. NOT "World of Warcraft/Interface/AddOns" where you install addons! If you wish to un-install it, simply remove the folders and WoW will load with the default textures again.