Great question!!!! I would like to know as well! BUMP
I've just had the implant put in my arm. I've had it before and love it. Also can have it in with breastfeeding so that's handy. Some people get really bad side effects from it though. It's trial and error really. If you do get bad effects the doc can just take it out. If it works for you it lasts 3 years. :).
I also had the implant in my arm. Got it shortly after having my son. I like that I didn't have to worry about it for a few years.