I am 30 years old and have never had any children. I had the Mirena for 4 months. During that time, I had no energy and I gained 10 pounds (probably a combination of both the hormones and my lack of energy). I was also very moody. I took two pregnancy tests while on the Mirena because my belly was so bloated and I was not having a period. I convinced myself the only reason I was gaining weight so fast was that I was pregnant (of course, both tests were negative).
After reading these posts, I realized my issues were probably due to the Mirena and I decided to have it removed. I had it removed 4 weeks ago. Removal was painless and my doctor was able to find the string easily. I only had light spotting for two days after removal and no pain. Within two weeks, the bloating had decreased significantly and I'm losing the weight I gained pretty easily (low cal diet and running). I had my first period within 3 weeks. The only bad side effect of having it removed is excessive acne on my face.
Previously, I used the Nuvaring, and I think I will go back on it. Even if I had read these posts prior to having the Mirena inserted, I still probably would have tried it because I rarely have medication side effects. I think everyone's body reacts differently, but I definitely could not handle the Mirena. I would absolutely recommend the Nuvaring, I only switched to the Mirena for ease of use and costs. Nuvaring does not come in a generic and therefore costs me about $40/month.