My endo says that my experience was unusually successful, but here goes:
I started taking cyp. acetate about 5-6 years ago. I started on 50 mg per day for 12 days out of 28 -- I also took Dianette.
I had a dramatic reduction in facial hair growth almost immediately (I know people say this isn't possible because it takes time for the hair to grow in the first place, but it seemed to be the case for me) -- I used to spend about 2 1/2 hours every day plucking out my beard, and by day 12 I noticed that the hairs weren't really replacing the ones I'd plucked -- by day 12, I was only having to spend maybe 15 minutes a day plucking. Maybe it's because my hair grows so fast -- maybe I was able to pluck a large percentage of them out by the root early on, and the cyp. prevented new ones from growing.
Anyway, I just stopped taking it two months ago (to give myself a chance to think of maybe starting a family). I may be imagining it, but it seems like the hair is already starting to grow back faster. Nothing like before, but just a few more hairs than while I was still taking it (I'd got down to only having to pluck every couple of days, but now I feel like I have to pluck every day again -- only for 5 minutes a day now rather than 2.5 hours, but I'm really worried that it will get worse as time goes on)
I'm thinking of buying some Saw Palmetto... not sure if it's any healthier than cyp. acetate (which did sort of scare me from time to time, all the warnings about liver damage and so on). I've also bought one of those electrolysis pad machines -- my theory being that the little @@##$$'s will be easier to kill off in their current fine state than they would if I let them get back to full coarse beard-hair proportions. keep your fingers crossed for me!
anyway, that's my experience -- hope it helps.