I had a ton of issues with Windows when my mother used it (despite me being a long time Windows user and offering her remote assistence). At one point I got so fed up with yet another update that fucked things up (=changed the UI she was used to) that I decided to install Ubuntu. My mother was happy with the new system and the number of times I had to support her was one thenth of what it was before.
OSX is also not without pitfalls, especially the updates can break a lot of existing setups (hardware...)
Linux is great for real power users or real beginners, not so great for intermediate people who know enough to fuck a system up for good. But if you are a beginner or a power user it just works unless you fuck it up.
With Windows and OSX it just works till they decide to fuck it up, even if you are trying to actively prevent it.