I gained close to 40lbs on it and had horrible heartburn (GERD). I had headaches all the time. When I got off it after being on it 2 yrs...my first period started back up a few months later and I THOUGHT I WAS DYING (and I've had 2 children completely natural!) I wouldn't recommend it to anyone. A close friend of mine started growing facial hair from Depo! It's not good stuff.
I was on Depo for about 5 years, and in that time I suffered more health problems than I have my entire life. I ended up gaining 100 lbs! As soon as I went off it, I felt much better but the weight didn't come off easily at all.
I was a long time ago. I gained 100 pounds in 13 months and then I couldn't get pregnant for 4 years. I have PCOS and endometriosis, and I'm not sure it's related to depo, but I'm not sure it's not either.