i had mine taken out after 7 months.
perfect insertion (didnt feel it at all, also found out i got a tilted uterus)
it was in the right place, no infections etc didnt gain weight, i actually lost weight.
But it caused me to have an iron defficency. I would have a period (medium bleed) for two weeks every two weeks! so i would bleed a constant medium flow for two weeks, have a two week break, then bleed for two weeks and so on. for the whole 7 months. i was told it would slowly settle.
the nurse was shocked that i was still in that cycle even after 7 months. she checked it again and prescribed me the pill for three months hoping it would regulate things. next day i had this horrendous pain like someone was ripping me open. that was it, i went straight back and got it removed.
no problems as it came out. been on the pill since and don't think i would ever have the mirena again.