I've had my Mirena for about 8 months and I have no complaints. I'd rather not use anything but I need to avoid conception for at least a year due to a medical issue, and the Mirena beats the heck out of the pill, at least in my experience. I did not find the insertion awful. The speculum was worse than the insertion, and I didn't even have cramping afterward.
The midwife recommended taking ibuprofen an hour before the visit, which I did and might have helped. She said the new recommendation is to start taking it 24 hours before insertion and take it every 6 hours until insertion.
At any rate, I had some heavy bleeding for two weeks and felt a bit PMSy for a few weeks but I feel normal and healthy now, and I have fairly regular, light periods now. I like the Mirena better than any other BC I've used (diaphragm, pill, condoms, contraceptive film.)