Answer:
I can't come up with an actual pro-con list, but really, they're a fun unique piercing that puts a twist on jewelry. That's exactly why I got them.
As for the cons below: mine has never gotten infected. In fact, your tongue is one of the fastest healing body parts, and it takes about 2 weeks to fully heal. Unless you're already partaking in really unsanitary actions, like licking phone booths, you're not going to get an infection. The only real concern, is knocking the back of your teeth. I've had mine done for a year and never had problems. It doesn't get irritated, or infected.
Literally, My only problem I've ever encountered, is that sometimes I get a spaghetti noodles wrapped around it.
