The Mac OS X interface looked so much like the Mac OS interface that users assumed everything was done the same, which it wasn't, so users had to unlearn old habits. The Classic environment in 10.0, although much better than in Public Beta, still had strange compatibility problems and quirky behavior. Like the original Mac OS, Mac OS X users' biggest complaint was speed - many felt the code name of 'Cheetah' was wildly inaccurate.

Mac OS X also provided Cocoa, the descendent of NeXT's very sophisticated OpenSTEP software development environment. Mac OS X 10.0 also provided all the standard features of a modern operating system - protected memory so programs couldn't corrupt each others' data, preemptive multitasking so programs couldn't hog the processor or lock the entire computer up, device drivers that would be loaded or unloaded as needed, and so on.

It incorporated a lot of the feedback provided by people that tried out Mac OS X Public Beta. Mac OS X 10.0 was released on March 24, 2001.

Preview mac os 10.0