I have my tongue pierced, 4 years now. It didn't hurt to have it done, the swelling hurt a bit, but nothing I couldn't handle. My naval hurt more. I love my tongue piercing, and I am sure my other half has no complaints either.

I switched out the metal ball with a plastic one, does less damage to the teeth, only downfall is that the plastic on holds on to bacteria more (thus smelling really bad when you take it out) and comes loose more often, but like I said, less damage. I haven't had any actual damage to my teeth, though I think I had a little erosion on the gumline, not much though. My dentist is always telling me to get rid of it, but it is too much a part of me to do. I talk fine too, only a little funny the first week.
Definitely find a reputable piercer, that will make a world of difference. There are all sorts of stuff out there on why you shouldn't do it, but a lot of those instances are really uncommon. If you go to a good person, then you will be fine. One nice thing about the tongue is that it heals fast, so if you decide that you dont' like it, then all remenants of it are gone with a matter of hours.
I recommend it, but that is my personal opinion.
