Talking desktop only here as servers are a different animal.
Macs of old were excellent machines, current macs are fairly standard PC hardware running Linux with a big price hike to pay for the fancy box and logo. Good machines but way over priced and over hyped.
The usability of most modern Linux distributions is at least on a par with Windows, the main problems are 1.people have prior Windows experience and 2.hardware vendor support for Linux is poor.
The hardware detection and built in support of some Linux distributions is in my experience far better than that of Windows (granted some are poor, all were poor not so long ago). However if you run Windows you typically have an easy solution as Windows drivers are usually provided with the hardware.
In my opinion operating system quality is not what it should be from any provider, to give a bike analogy would you rather pay for a cheap Chinese made scooter (Windows) or get a one for free with the throttle on the other side (Linux) - there is some value in familiar controls.
I've managed systems ranging from TI990's, RS/6000 running AIX, Win 3.1 through to 2008 servers and desktops, Ubuntu servers, Mepis desktops etc.
We're now getting well off topic.
