I see so many bad reviews; mainly on shipping, customer service, etc. Honestly I've had a great experience with them overall. In several orders, only one shirt didn't perfectly fit. It was slightly big and I gave it as a gift to my mother who loved it. I always think the quality of the material is fine, and have had many wears on most of the items including after washing. A few of the tunics were a little thin (wear a coat!), but have held up 100% to wear and tear just fine. Perfect for the money.
As for shipping and the possibly long waiting periods... people need to understand how the site works. They advertise items from different brands, and when someone makes the order, they send it over to that brand, who THEN ships it to Zulily, THEN to you. This can take some time and not completely in Zulily's control. If you only scroll down the page some, and read the full description, it clearly marks the time period it'll ship out. If you're okay with it, go for it! If not, simply don't buy it. I've had tracking on all my items, which was accurate.
Now, I have had a few instances where Zulily didn't quite deliver per say. Once, I recieved the wrong pair of leggings. I called customer service, and without any arguing or prompting, the lady immediately refunded my money in full, set up sending me the correct pair, told me to keep the ones I got, AND gave me a $15 credit amount. Never seen that before! Also, there was an item that was promised to ship on or before Christmas, and later it got changed to arriving late. I called Zulily, who refunded my money in full, and told me to keep the item when I got it. So whilst I normally would rate them lower b/c of these instances, their customer service more than made up for it.