We have been selling on Bonanza for about eight months and it has been a great experience for us. The similarity in interface between Bonanza and eBay make it easy for sellers and buyers to navigate the site and their reasonable advertising offers are helpful in getting your products out there when people google for them. Their integration with PayPal also makes it easy to use your existing account.
We have found that what currently sells best on Bonanza are items that are not already saturated on eBay and Amazon. If there are a few sellers that sort of own the marketplace on eBay and Amazon it will get passed over on Bonanza unless you can provide a significant cost break. The reason is that people are not going to go out of their way to create another account on yet another eCommerce platform just to buy there. There needs to be a price incentive and/or the product needs to be relatively hard to find on the other sites to make it worth a buyer setting up a new account.
Selling on Bonanza also tends to be less expensive than on eBay and Amazon and this can be an advantage for sellers looking to provide a cost incentive to potential customers.
Support from Bonanza has been really good on the few occasions when we had to use them. Most of our support issues have been clarifications of how the platform works with really only one issue early on when email alerts were not being received. It is nice that they provide support via email as well as by phone. Unless it is an urgent issue we would rather use email support where there is time to accurately communicate an issue and respond when it is convenient for our schedule. It also provides a nice knowledge trail to go back to should an issue reoccur.
We are planning on growing our presence on Bonanza as it gives us a great backup eCommerce site should eBay suddenly make a change that would prevent us from selling there for any reason. Policy changes from eBay and Amazon can be disruptive at times and Bonanza provides a nice stable platform where we have not seen these kinds of machinations occur.