Hey Joe! Well, I am all for pierced nips! I find them sexy as hell on men and women. I absolutely adore mine, and my only regret was waiting so long to do it. If only I had known what an improvement in sensation I'd get....ohyeah.
The piercing itself, FOR ME, did not hurt. It was a very strange, electric sensation. It was intense and a very sexual experience for me. I greatly enjoyed my initial piercing, but I will say that when I went back 6 months later to have them stretched up a gauge it was more of a painful sensation, but over quickly. The day after was the worst; my nipples were very sensitive and sore that day.
You can't really judge your experience on anyone else. Some people hated it and think it was the worst pain they'd experienced. Some people (like me) really enjoyed the experience. It depends a lot on your mindset, and your reasoning behind getting it done.
My main advice would first to make sure you find a GOOD, reputable piercist. Just with any body art, you need to go with the best, because your body is worth it. Make sure they are licensed, make sure they are sterile! No piercist (or tattooist) should be eating/drinking/smoking while doing their work, things like that. Make sure they use new equipment. Make sure they have an autoclave...all the basic stuff.
Follow directions for cleaning! The better care you take of them, the better care they'll take of you

That means cleaning them twice a day. that means taking care of them religiously. Be gentle on them for the first few months (
especially with mouths! Mouths are filthy to have on an unhealed piercing of any sort). Mine honestly did take about 6 months to heal completely, and then I had them stretched up, so I started some of the healing process all over again. They will hurt a bit at times, especially if you happen to catch it on something. It will ooze for a while too, and having some crusting around the rings. Again, be religious in your care and cleaning for them, and they'll do you good.
Oh yeah...and my other advice? Take pics and post here if you have it done!!! I looooove seeing decorated bodies!

hehe...
*hugs*
Mae
Here's a closeup shot of the 12G I have in now. Yep, twisted metal, kinda ribbed. Feels damn good when they slide through....*shiver*