I am african american and I have had fraxel on my thighs and buttocks and love the results. I have had 2 out of a recommended 6 treatments and I am very happy. There is already a noticeable difference. They obviously won't be completely gone but they will be much lighter. Like anything it depends on your skin and your doctor.
so far I haven't had any problems besides the itching and peeling skin afterwards. You are also left with little brown dots but they fade over a couple weeks.