i haven't usedv the yasmin pill (i don't think) but i have used a pill that also helps acne for quite a few years.
i use the diana/estelle pill (one is the cheaper, generic version - which i usually choose). i've found it to be really good - i certainly don't get the nasty (painful) hormonal breakouts like i used to.
i found my dr was really good in discussing it with me - we talked about the sort of pimples i got & whether it was linked to my period etc and she decided that this was the best pill for me. overall i found it a very consultative process.
it did take a couple of months for it to really kick in and make a difference, but now i hardly ever get those pimples & sometimes when they do start, they just go away after a day.
my dr also recommended an antibiotic lotion (because i didn't want to take anti-biotics - a dr had put me on them for over a year for my skin previously & then when i had to take them for tonsilitis a couple of years later my stomach was upset constantly) to help with any breakouts that did happen & to help take redness & irritation out of my skin.
i find now that my skin has changed & i recently had to start using products for dry skin - which is a huge turnaround for me! i bought ella bache products - they're not cheap but i went to a beautician and she looked at my skin with the special ultra violet light etc to show me where it was dry or oily etc and then recommended products to suit (the consultation was free). i found this took my skin from no breakouts (courtesy of the pill) to looking really healthy (because of the moisturiser). having improved the quality & look of my skin has improved my confidence heaps.
i think overall it's a combination of things that have improved my skin.
sorry for writing an essay. i hope it helps a little!
good luck at the drs next week