I am a regular shopper on Zulily. I love it for the unique clothing that I can get for my daughter. The site is very up front about why the items take a while to ship and so I just shop accordingly. The customer service is great and I have even been on the phone for upward of 5 minutes with a rep while he explained the process and why it takes 4 weeks sometimes to get your item. When I ordered something and it was out of stock, they credited my account and gave me a $10 credit. For my daughters clothing, I love it.
I have oredered shoes for myself and some home goods from the site and have been pleased. I will say that the size guides have proven unreliable when it comes to clothing for adults. Unless I know exactly how the brand fits me, I stay away from ordering my own clothes. Kids are much easier to fit, though.