If you have a 500GB hard drive and a slow internet connection (less than 10 Mbps), then yes—searching for is your only way to experience Treyarch's masterpiece. The loss in quality is negligible (mostly just removed language files and compressed installer headers), and the Zombies mode runs flawlessly.
However, if you value official updates, safe files, and online multiplayer with friends, wait for a Steam sale. The convenience of automatic updates often outweighs the 80GB of saved space. Download Cod Black Ops 3 Highly Compressed Pc