I had my tongue pierced for about six years and absolutely loved it (although not as much as my old fella did). It didn’t hurt at all, I had it done by a properly apprenticed and trained pro who also happens to be a friend. It took a couple of weeks to get used to and for the first while I sounded like an absolute f@#!wad… my piercer used a longer post at first to allow for the initial swelling, so I was clicking and ticking like a Kalahari bushman… but it was my fave piercing.
All those horror stories you hear, tetanus and brain abcesses and stuff, if you use the proper clean equipment you don’t need to concern yourself with that. But I’d advise going to a good piercer because there’s a slight chance of hitting the trigeminal (sp?) nerve in the tongue, and that would suck. Pun intended.
Eventually I had to take the piercing out because I ended up knocking out a bunch of front teeth, and had to have a series of dental surgeries, and I had to keep taking it out for x-rays. And my dentist hated it – she constantly warned me I’d chip my teeth – and while that never happened, I still have a bit of bone loss in my lower palate from where the end of the stud rested.