I've actually gotten a nipple piercing, and I'm not going to lie, it
HURT! I was squirming in the chair during penetration of the needle and kicked my feet up a little bit.

The cleaning process isn't hard, though. You just have to put some gel on it while you're in the shower and then spin it around a little bit- it's actually kinda fun to do.
Just be careful when taking the piercing out, because the opening seals up FAST! Like, within hours.