what are the advantages and disadvantages of selling directly to the customer vs. through a channel intermediary such as Wal-Mart?

Direct selling is when manufacturers connect directly with customers and sell their product to them without using intermediaries like retailers. this has several advantages, for example, it enhances stronger customer relationship with the manufacturers which selling via retailers doesn't provide. This way they can make changes to the product based on direct feedback from their customers. Additionally, these manufacturers can use this direct selling method to learn ways on how to best serve their customers. It also reduces holding costs which is incurred in order to have their products on retailers' shelves.