I don't know if it's so much about UI. For a total novice I'm not sure if Unity would be harder to learn than say Windows 7, assuming unfamiliarity with both.

I don't know if it's so much about UI. For a total novice I'm not sure if Unity would be harder to learn than say Windows 7, assuming unfamiliarity with both. It's really down to compatibility and of course with a more common OS there are more friends and relatives that you can ask for help. Compatibility with old software can be a big deal for some people too, for example my mother struggles to understand why she can't just keep using the same version of Wordperfect that she learnt in 1994.