Dont have Norplant but have Implanon which is a similar implant in the upper arm. I had it in on 3 December and all went well. I started bleeding on NYE and havent stopped yet! I am beginning to think that if it doesnt show at least some sign of stopping in the next couple of days I am going to have it removed. However, dont let my horror story stop you, I think there are some folk for whom it works very well! It may be doing funny things for me because I am actually using it as the progesterone component of my HRT (the oestrogen is also implanted)
I'd say that if you are one of the lucky ones and get the "no periods for years" result then it would be fantastic!