Got Mirena #1 put in under general anaesthetic at the same time as my diagnostic laparoscopy, hysteroscopy and laser treatment for endometriosis, which was before I'd ever been pregnant.
No side effects other than not having periods- which, for me, was AWESOME.
Removal was a breeze (like, no pain, no bleeding, nothing), probably because I took some misoprostol/diclofenac beforehand.
Got pregnant within 3 months of removal, which was quicker than we expected, but still meant I had 2 totally sucky periods to deal with.
At 3 months PP (after elective c/s), and still amenorrheic from the breastfeeding, I went to get my second Mirena.
My cervix did not play ball- refusing to dilate enough for insertion, even with a cervical block (which wasn't as horrible as having someone inject local anaesthetic into your cervix sounds like it will be).
So 6 months PP (still no periods) I had my second Mirena put in under GA, which, again, was fine- 1 day of tiredness from the anaesthetic, no cramping, no bleeding, nothing.
Here I am almost 2 years later with only a handful of days of spotting since, and absolutely thrilled with it. No mood issues, no acne, no weight gain, nothing.
Between Mirenas, pregnancy and breastfeeding I've only had 2 periods in the last 5 years, and I couldn't be happier about it, given the absolute misery they caused me.