I have had two - one for approx. 3yrs before DD and one fitted about 3mths after she was born. First one was absolutely marvellous - no periods, no moody side effects, but then I was living a different life then, so probably didn't notice amongst the hangovers!
I had the second one removed after 3yrs as the mood swings were getting appalling, with the interval between them growing ever shorter and I was borderline pyschotic at times - really rather scary. Weepy, emotional, depressd, violent rages, fat - not a pretty sight! Now, 5mths on, I feel almost back to normal and am a lot nicer to live with. I think that I just can't do hormones any more after the upheaval of pregnancy. I suffered from PND for the first 12-18mths after DD was born and this could have been partly due to the presence of coil hormones or may have masked the effects of the coil - I am sure most docs would poo-poo a link, but I am not sure...?? My doctor did concur that moods swings were a known side effect, when she removed it but I don't think this is something alot of them admit.
Also, it KILLED my libido stone dead. Happily it is just starting to re-emerge!
I think it is a marvellous form of contraceptive for those for which it works - no periods, hassle free. However, if you have a pre-exisiting intolerance to the pill/hormones, I would proceed cautiously and be aware of the possible side effects. For all those who are happy with their Mirenas, I am extremely - it is such an easy form of contraception. I am toying with a non - hormone coil or sterilisation as I can't do condoms and the rythym method is just a little too scary for me to be a long term solution to NOT getting pregnant!
It was mildly uncomfortable to put in both times, but no worse really than a smear and I didn't even notice them taking it out ( apart from the fact I was lying on my back naked from the waist down with my legs in the air, that is!)