Pros
Stitch Fix has done a great job of promoting a healthy culture. We have a focus on hiring smart, motivated, and kind people, which makes it that much easier to trust and work with coworkers. I've seen very little hierarchy or politics. Instead there is a culture of teamwork both within and across departments. Benefits have recently improved, including better vacation and generous family leave (6-16 weeks).
Cons
We're growing fast, which means that a lot of energy right now goes towards hiring and onboarding, and communication across large groups is getting harder. We don't have all the perks that some tech companies might--we only get catered lunches 1-2/week and there's no dry cleaning or housecleaning services. I don't consider this a big con, but I guess some people might.