Pros
Fantastic culture, great benefits, nearly unlimited room for personal growth, and great work/life balance. Beyond building up each employee and truly investing time and efforts in them, Zillow provides an atmosphere that makes you want to be there and work hard as the company is doing the same for us. We just recently had "Engineer in Training Day" which allowed us to bring our children in to work (it was synched up with a school holiday too). There were over 250 kids from ages 3 to 18 and the event was so much fun and so well organized. My 5 year old absolutely loved it and I did too. Zillow also brings in guest speakers to help widen our views and learn what it takes to be highly successful.
Cons
Come here and try to find some, I haven't found any cons so far... pay is competitive, benefits are great, atmosphere is fun while not missing the goal of growing and improving to become a better website/product.