I haven't tried it but from what I have read and heard it really isn't so great for PCOS, and for lots of women can cause PCOS-like symptoms. Not being negative, just what I have found out from discussions with doctors. Would be a pretty simple bc but I think it is too androgenic (etonogestrel is derived from desogestrel, which, when combined with oestrogen can be a great treatment for PCOS, but without can be too androgenic), and since it is progestogen-only, would make periods irregular or cease altogether. The oestrogen is needed for PCOS to inhibit androgenic activity which causes the problems.
http://www.netdoctor.co.uk/medicines/100004325.html
However, some women have great success with it, it is safe to use when breastfeeding, can lessen pain and make periods less troublesome. Hope this helps! Why are you considering it?? You could perhaps try the NuvaRing to see if you at least tolerate etonogestrel (with oestrogen) and then decide..?
xx