I went off the pill 12 years ago and started on Yaz in the summer of 2007. I had pretty significant mood swings for about two weeks on the first pack. In fact, it was like the worst PMS I've ever experienced, with my anger and rage surging up for no apparent reason. The mood swings were gone after my first period, though. The only other problem was that my first cycle lasted 10 days, the second 7 days, but by the third pack my periods completely regulated to a light, 4-day cycle.
Since the "old-school" pill had made me gain weight, I was expecting to do the same on Yaz. To my surprise, that didn't happen. Also, I didn't experience any PMS at all, before, during, or after my periods. I only went off Yaz because of surgery for fibroids on my uterus resulted in a uterine hysterectomy last month.
The older brands of birth control come with many warnings of potential blood clots and other side effects and, while I am sorry for the illnesses and losses people here have experienced with same, every prescription medication has its risks. Yaz was wonderful for me!