I wouldn't. Turning someone off to "GNU/Linux" (which is used to describe
several operating systems that are rather different) would be a huge loss.
I think someone who is used to Windows needs to be introduced to something
like Ubuntu GNOME before trying Trisquel, and they need to learn about the
issues of things like Flash and proprietary drivers/firmware. Without knowing
about this stuff, someone who tries Trisquel will just think that it's no
good as an operating system and go straight back to Windows.
But before you can go to an entirely different operating system, you need to
get a feel of it. Tell your friend about LibreOffice, the GIMP, and other
free software which is (and this is important) relevant to them. Some other
time, you can show them GNOME, Unity, KDE, and/or Cinnamon and tell them of
the imperfect from the freedom dimension, but easy to use operating system
appropriate: Ubuntu GNOME, Ubuntu, Kubuntu, or Mint. Once they are
comfortable with whatever OS you showed them, and if they've heard about the
freedom problems in it, Windows, OS X, etc, *then* you can tell them about
Trisquel, that it's basically the same as the system they're using but
without proprietary software.
Don't push them too hard, however; if they feel that they need Flash, Skype,
or some other proprietary program, be compassionate about their situation.
it's better to have an Ubuntu user who understands and appreciates the free
software movement, but feels they are not ready to abandon certain
proprietary programs, than to have an Ubuntu user who is convinced that free
software advocates are assholes or a Trisquel user who is unhappy with the
free software-only experience.
