It hurt me to get it put in, pretty bad but it was over really fast.
Women with an IUD are supposed to have less side effects than with most hormonal birth control because the hormones are less and more localized.
It almost always lessens your period, and in about 20% of women makes your period go away altogether (it did for me)
It's extremely effective, easy to use, convenient, and cost-saving in the long run.
When you have it, you should check the strings (feel up inside your vagina for two fishing line-like strings coming out of it) to make sure they are there. If they aren't, it's a sign that the IUD has shifted or fallen out and the IUD is no longer effective. This is rare, but if it happens you need to get to the doc asap. (Didn't happen to me) You need to check them often in the first couple weeks and once a month after that (like during your period).
The only real downside to it is if you are one of the women who do get side effects from it, it's a pain because you have to wait it out for about 6 months (which is how long they say it will take for the side effects to go away) and then go get it taken out which is a really easy and painless procedure but you have to get the appointment and everything.