I did have some issues up front with insertion and string length, but beyond that I had a good experience and would have gotten another if DH had not opted for a vasectomy instead.
Insertion: Doctor put one in and I was super uncomfortable/in pain. Checked with ultrasound and it was not in correctly. Removed that one, got another, and made multiple attempts to insert that did not make it through my cervix. Was sent home with lots of cramping and no IUD.
Returned a few weeks later for another try. Inserted easily. Major cramping that afternoon and evening.
I remember the bleeding/spotting lasting for quite a while (maybe a few weeks in and off), but after that I really did not have a period the 5 years I had the mirena.
One other issue for me was incorrect cutting of the strings. They were too short and cut at a sharp angle. (Think more like stiff/sharp fishing line sticking out just a tiny bit so it’s rigid rather than a than a soft longer string.) DH discovered this during our first few attempts at “intimacy”. I thought he was over-reacting, but I actually cut my finger when I checked myself. I returned to the doctor and told him to either fix it or remove it. He wound up just cutting the strings shorter so they did not stick out of my cervix at all. This, of course, made me unable to ever check the positioning with the strings.