The product and service can be either amazing or horrible. Depends on the company they are working with (or selling from). If it is not a Teambuy product, make sure you look up the company they are selling from as Teambuy will have pretty much washed their hands of any customer service (you will have to contact the direct company yourself, goodluck.).
Ordered a few items with everbuying.com. Paid extra to have items shipped faster but was not notified of out of stock item. Only when I inquired did they let me know that none of my order had been shipped out. The items were great when they arrived.