No acne and no extra body hair whatsoever either. I used to get HUGE zits when my period was due. I haven't had any zits since I started using the Mirena, but I haven't had a period either.
I was told to not use the oral contraceptives as they contain estrogen which disagrees with my liver. The Mirena and the Implanon are the only devices that do not estrogen and are the only way of contraception I can now use.
Have had the Mirena for 2,5 years and am very very happy with it. It is even more accurate than oral contraceptives. My liver function tests have returned reasonably normal since then.