I have ordered around 10 times from Zulily (in Canada) and overall the experience has been great! I heard about it through a colleague how has also has good experiences. I have received some absolutely beautiful and fun pieces.
When an item never showed, I contacted their Customer service by email and promptly received a refund.
A few times I received piece that were lower quality but the price was always reflective of the quality. I have also learned to read the description of every item before purchasing (dimensions, type of fabric, etc.). And when I feel like there aren't enough pictures to properly see the item... I don't buy it. Simple as that.
Overall positive experiences for me. One tiny thing is that they could have more pictures of their items or allow for a proper zoom.