What does it do?
Sets up PayPal transaction for you
Lets the buyer download your eBook the instant they pay
Buyers can review your eBook as well as rate it
Allows seller to optionally discount eBook for premium members
Image/YouTube video can be embedded within the eBook description
It protects the seller from fake bad reviews/ratings since only actual buyers can rate/review.
It protects the buyer from fake positive reviews/shilling because only actual buyers can rate/review. Also, no one can sell a duplicate eBook.