I have a Mirena and love it. It took 3mths to settle down. I now get no periods at all. I will say that I am now in the 40+ age group and year 4.5yrs of my current Mirena.

A GF of mine has just had one put in for heavy bleeding, it's taking a while to settle and she is having irregular cycles, she has been advised to persist for the full 3mths before giving up.

My OB's recommended only for the fact that I was finished having children.