Ursa and Ursa-Basic is optimized version of Ardis icon set, which provides better user experience on smaller screens but it also works great on large displays.
Both icon themes are perfect choice for everyone who loves simplicity. You can support creator by purchasing his icon themes Ardis & Ursa, also visit creator site. You can use Unity Tweak Tool, Gnome-tweak-tool or Ubuntu-Tweak to change themes/icons.