Apple wisely continued to ship Mac OS 9.2.2 as an option for Macintosh users, who were not used to the revolutionary, but baby OS that would take until 10.2 'Jaguar' to fully mature. Finally, independent benchmarks had shown that copying and transferring files in the gold release was slower than on OS 9. While people liked the new Aqua UI, and found it innovative and fresh, the Dock was criticized as an issue for usability and yet others missed the customizable Apple menu from earlier Mac OS versions.

Furthermore, several features, such as labels in the Finder, the ability to burn CDs and the DVD Player, were not present as they were in OS 9. Aqua was slow, was careful in rendering elements and scrolling, and favored cleaner redrawing, leading to an impression of sluggishness on this system. Mac OS X 10.0, similar to the Public Beta, sported a new UI called 'Aqua', which featured all-new water-like UI elements, animations, and a new rendering engine that supported advanced compositing at the time of its release and PDF support. Despite it's tremendous internal changes that allowed complete Posix support and new frameworks, Mac OS X was not without criticism when it first launched for $129. Several new applications were written for the new operating system, and others, such as the Finder, were rewritten in the Carbon framework. It was the first version of Mac OS that was based on top of new UI frameworks adapted from the NeXtStep OS, the Mach microkernel, and a fork of FreeBSD UNIX nicknamed 'Darwin' by Apple.

Mac OS X 10.0 'Cheetah'' was the first officially released copy of Mac OS X for the public, after the aforementioned Public Beta.

Mac os cheetah