Here's some info on Norplant complications:
Some complications that women using Norplant commonly experience include acne, headaches, weight change and breast tenderness. Norplant also increases the risk of functional ovarian cysts. Although these cysts usually dissipate spontaneously and do not require surgery, they can cause abdominal pain. The most widely experienced dissatisfaction is irregular menstruation: "In the first year of use about 75 percent of Norplant users report some irregularity in menstruation, from amenorrhea to excessive bleeding" (NOBOS, 291). The synthetic progesterone contained within Norplant imposes an artificial control over the menstrual cycles and women are often upset by the sporadic bleeding that results.
You can read the whole article at this site:Norplant
Here are the complications with Implanon:
The commonest side effects associated with Implanon are irregular periods, weight gain, acne, headache and breast tenderness. As with other hormonal methods of contraception, many of the effects will improve in time. Most women have regular periods after the first year, but around one-third of women still have irregular bleeding, which can be heavy and frequent, although this is less common. Some women lose their periods completely. It is wise to expect some change in your periods initially.
Rarer side effects include hair loss, mood changes, change in libido, abdominal pain and painful periods.
You can read the rest of the article here:Implanon
As you can see, Norplant and Implanon have almost the mirror image in regards to side effects.