I use Mirena too. I've had it since shortly after I had my daughter. It's time to get it replaced (mine was good for five years, though I hear they now have a ten year version) and I LOVE it. There have been no negative side effects whatsoever.
After I had it placed, I bled for about four weeks, first heavy, then it slowly got lighter and lighter, and I haven't a single period in the past five years. NOT ONE. It's awesome.
Now that it's expired and I need a new one, I thought I'd perhaps start my periods again, but I haven't. I should have had it done in April, but have had other medical issues to tend to. (One thing at a time.)
Now, I'm 36 and a smoker, so my options are limited by those factors, but I have to say, I would choose Mirena over anything else they offer. It's been so easy, so painless, so awesome... I'd say it actually made my life better. Lol!