I have never had a piercing (not even ears, and not tattoos - I am a big baby about pain!), so I can't speak from experience. But every time I see somebody with a pierced tongue, all I can think of is rotting food stuck in it - not an appealing thought! Even if that doesn't really happen, others may find it gross because of those thoughts.
OTOH - if it really appeals to you and your girl friend / boy friend, etc, and you have researched it and feel it is safe and not too painful, then go for it! Doesn't really matter if some people think it is gross looking, as long as you, and people you care about, like it.
I BELIEVE (but don't know for a fact) that you can take it out if you have to go to a job interview, or go to work where it is not allowed, so that would be a main concern alleviated. And I BELIEVE you can remove it and allow it to grow back, unlike a tattoo. If all of that is true (I would have to research further to be sure), then I would advise any close friend who asked me, to go for it if they have the money and they like it, even if I personally find it unappealing.