Hi T.
Well I guess I have to be the negative in the all the positives, I was the 1% that didnt take to Mirena. I had my inserted in Feb 06 about 3 months after I had my last kid. I didnt have much discomfort with getting it inserted and yes a little cramping afterwards and some spotting but all seemed fine, then about 3 weeks after I started spotting all the time and if i exercised or exherted myself at all I bled for the next 4 days constant, then back to spotting, my body just wasnt accepting this in my body, I went back to my OB who told me to give it 6 months for my body to adjust so I did, after 5 months I went in and had a ultrasound to make sure it was in place correctly and it was then he put me on birth control to help my body with the inflamation and bleeding and it helped a bit but still spotting every few days. so at the 6 months I had it yanked and hubby got a vasectomy instead.
my OB said my symptoms were rare but wanted to let you know it can happen, its just not for everyone, but stick with it for at least 6 months before you talk to your OB about it