I didn't have a period on it. But I didn't like it. I had it removed after I think eight or nine months. There were enough side-effects that made it not worth it, I just went back to depo provera instead. My insurance covered it but it still cost a few hundred bucks. Placement was painful as hell but only for a moment, after I had it placed I read on another forum "don't let them fool you, it feels like a strong contraction when they place it" from a woman who did have children, and a few others chimed in "that's EXACTLY what it felt like" - so I don't think having kids or not is going to make a difference on the pain factor. Never having HAD contractions I can't tell you yes, that's what it is, but it was so painful my body literally curled up off the exam couch in response. But that was about it. Ow ow ow then it was over.
After that it was just cramps for a few days but I just took fistfuls of Ibuprofen and it was no big deal. I think three, maybe four days is how long the cramping lasted. I bled the first day when it was placed. Not even spotting after that.
There are two ladies on here who had theirs migrate in their body IIRC, I know one for sure and I think the second one said the same thing but it's been a while. My cervix tips, the Mirena itself didn't move, but the cervix moved around and the Mirena therefore moved with it and it... erm... sat in some odd places at times. Not a fan. Creepy and uncomfortable.
Ectopic pregnancy is also a risk. One of my co-workers in radio had an ectopic pregnancy while she had an IUD and told me it was one of the worst experiences of her life. I found stats somewhere not that long ago about how common ectopic pregnancies are with IUDs and it was surprisingly higher than I would have expected. I knew it was a risk but of course the doctor didn't tell me how much of one (they never do.)
Honestly, if you think you want kids some day, I wouldn't do it. If something happens and you can't have kids... I mean, everybody has to weigh their own risks of course, but for me, if I wanted kids, it wouldn't be worth the risk just so I could avoid taking pills. The only reason I tried it was because I knew if something happened and it damaged my uterus so I couldn't have kids, I'd be glad. =P Same reason I don't care about if something happens from the depo provera... if it makes my uterus shrivel up and evaporate, hurray!! But not everybody feels that way obviously. I also don't recommend depo to anybody who thinks they want kids and I like it just fine.
Besides the IUD there's also Implanon, the rods you get injected in your arm... Lyzelle has (had?) that and had a rotten time on it, you could ask her more about her experiences with it. I was thinking about getting it after they took the Mirena out, but it was also a few hundred, so... I didn't want to spend that much after having the Mirena fail. I just went back to the depo.