Boy do I wish I had come across this site before I had my Mirena inserted. I had just had my second child and decided upon Mirena for birth control. My physician told me I could safely have it inserted at my 12 week check up. She insisted that the amount of hormones emitted were so slight that they would stay localized in the uterus. So no, I would not have any increased acne, wt. gain, or more problems with depression then I already have.
As with others, the insertion was more painful than I expected. Keep in mind that I had already been through labor and subsequent C-section. I spotted (and cramped) almost every other day for the first 3 months. How could it NOT be effective birth control when I could not fathom having sex!
I had just gotten over the initial problems associated with insertion when I recieved a call from my doctor. She informed me that in several of her post partum Mirena users, the device had perforated completely out of the uterine wall. Evidently because the uterus continues to shrink for several months, and it is spongey after pregnancy there is a real possibility of the thing sticking into the top of the uterus at insertion. It can then corkscrew outward. Or, the uterus can shrink down and force it out the top.
Needless to say I opted to have mine removed. Not until it was out did I realize how I had been suffering in many other ways besides the constant bleeding. I was very depressed from the hormones and having all sorts of skin and weight issues as well.
I think for someone who is not hormone sensitive and is at LEAST 6 months post partum it might be a nice option for birth control. I just wish I had been much better informed.