I'm all for yoga, but I wouldn't consider it cardio. Strength training, perhaps.
For me personally it has lowered my stress level considerably...I was to the point I was so stressed out all the time that people were telling me I needed medication...after only a couple days of yoga I was so much calmer. After a monthly of doing it near daily I saw significant slimming in my midsection, plus a lot more strength throughout my entire body, but especially my core. I have genetic back problems that have caused me fairly constant issues since I was 12, but I haven't had a take a single pain pill for my back since the first week of yoga. And then there is the added bonus of making me feel really sexy and powerful.