I have been a member on Zibbet since it launched in 2009. I also started a shop on Etsy at the same time. Etsy was already several years old and had built-in traffic, so I made sales there. I was struggling to keep my Zibbet shop up with my Etsy shop, so I emptied my Z shop.

During this time, I've heard WAY more negativity about Etsy than I ever have about Zibbet. Why? It's all in where you hang out. Go to the forums on Etsy, and you'd think no one ever sells a thing, Etsy is greedy and charges more than what they should (even though it's quite thrifty when you start comparing) and they won't leave things alone.
I've only heard a couple of things "wrong" with Zibbet (again, it might be where I hang out!), little to no internal traffic and people that got charged again for a reoccurring payment. I don't put too much strength behind the charges that people are blaming Zibbet for. Mainly because if they went to Paypal in their settings, they could (and should) disable to reoccurring payment to Zibbet. Done.
The complaints about no sales on Zibbet? Those are more valid, BUT; we don't know what they did to drive traffic to their own site or how long they had their shop. A shop that is there for two months doesn't gain any clout with the search engines, so it won't get traffic there. The marketplace does have poor traffic and will continue to do so until the site grows. Zibbet may grow slower simply because of the vast Etsy shadow, just like Etsy is dwarfed by eBay.

Finally, Zibbet is just now making some nice strides. They announced a major improvement this week https://blog.zibbet.com/blog/zibbet-is-changing-our-biggest-announcement-ever/
It is exactly what I need to get my shop going on Zibbet AND Etsy.