I never had an IUD either and I love it. I got Mirena a few months ago.
It wasn't really painful, so much as very uncomfortable. Think of a regular exam combined with a crampy period.
I was instructed to take one of my high mg motron from my c-section 1 hour priot to my insertion to help with the discomfort. I had a little bit of spotting afterwards for ike 2 days, but nothing major. I cam back a month later to make sure that it was still in place and it was and it has been great.
I haven't had a period since (although I do have PCOS and didn't really have a period before that either).
Just make sure to talk to your doctor, but I would recommend it to anyone who doesn't want to mess with the pill. I want another child, but not anytime soon, and this way I don't have to worry about b/c and forgetting to take the pill.