I had one and my experience wasn't so good. Please don't be scared but just keep this in mind if you have issues. I share it because it wasn't out there when I needed it.

Basically I got it for heavy bleeding and it made my bipolar go wild. I had it for nine months and was suicidal and moods were everywhere the whole time. Finally we decided to pull it and that it was better to put it back if needed than to run the risk that it was causing the problems. Out it came (out is really easy btw; I was having another procedure under anesthesia when it was inserted so I know nothing about that) and I improved almost immediately. I did have even heavier bleeding and a hysterectomy after that (so glad for the surgery) but the mood thing surprised everyone. Yet within a few weeks my pdoc and gyn both found other women with mood disorders made worse by Mirena, something neither had knowledge of before me.

So it is rare but just know that if you have more mood issues you should discuss the possibility of an issue with your doctor.