Sellers beware. This service has really poor support for Sellers. First of all, they an unprecedented 20% of your sales, (including shipping costs if you sell tangible goods. So you have to charge more in shipping to recoup your costs) The customer support is non-existent. Most of the time they'll tell you it's not their problem. I actually had one customer support guy respond to the question in my help ticket with a "we'll see."
They'll screw you at of your money any way they can. Instead of letting you collect money directly through Paypal, like Etsy or Ebay, it goes through their system, and they hold on to your revenue for 3 weeks while it "clears." In this day and age of high technology, there's no real justification for this. What are they processing the transactions by hand? What this really allows them to do is keep your money for any reason they come up with.
The quality of most of the gigs are pretty low, and Fiverr seems to poor quality, blackhat SEO and backlink gigs in order to rake in more $. This is going to hurt them in the long run though.