Using Google to search, I didn't find much in the way of reviews, perhaps because their name triggers many similar websites.
I would read their contract/sales agreement carefully. If they want money upfront, I wouldn't use them. I'd only use a company that takes an agreed % of the sale price. (like Ebay) There are many such consignment services available, if in doubt, go somewhere else.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI