I was going to get one, did all of my research and went for the appointment, but it turned out that I had too much cervical scarring (gee, could that have anything to do with pushing out a ten pound baby with his arm up over his head??) and due to that it was extremely painful.
I had discussed it with friends who had them and they had mixed reviews. One, who has had it for four years now, LOVES it. She said that she can't feel it, only had slight cramping after insertion and has not had ANY issues with it.
Another one said that she couldn't get over the fact that there was a foreign object in her body and had it removed after two weeks.
While researching it, I found that the IUD's of today are much safer than those of the 70's. It does prevent implantation of eggs, sometimes fertilized ones, but I'm pro choice so that doesn't bother me, and because pregnancy doesn't began until implantation it really wasn't an issue for me.
I would have gotten it, had it not been for the scarring, because I like the idea of not taking hormones, not having to worry about my birth control and being able to have spontaneous "relations ;)" with my husband without the fear of pregnancy.
Good luck with whatever you choose.