Etonogestrel
"I got implanon on Christmas Eve 2012 and I'm making an appointment to have it removed- it's now March 2014.  At first, I had periods for several weeks.  Then, later I would spot here and there. I believe after a good 6 months being on it I haven't had a period, spotting, nothing.  So that part is fantastic. Not pregnant. Another plus. 

Bad parts?
I have easily gained about 5-10 lbs and I can't seem to shed them no matter what I do.  About 2-3 months after Implanon I developed seborrhoeic dermatitis around the crown of my hairline.  I've tried everything and it will not go away (i.e.- cradle cap for adults basically). It's bad, like really bad. I've read reviews/side effects and it's named as one.  Ugh."