Tell the Real Story – A case study does a better job of engaging the reader than ordinary brochures or data sheets. It tells a compelling tale about a "hero" (your company) who used a "mythical weapon" (your products or services) to bring about a "happy ending."
A Customer's Endorsement – A good case study tells the story from your customer's point of view. In a sense, your customer is providing a "seal of approval," explaining how your company provided an effective solution to their needs, and why your product worked for them.
Much Better Than a Testimonial – A case study is a road map of the "Buyer's Journey." It outlines the customer's problems, the solution that you provided, and the benefits your customer received from it. This makes a case study more convincing and persuasive than an ordinary testimonial blurb from any client.
A Great Sales Piece – Case studies are great collateral for closing sales. When you send one to a prospective client, it can help them to make up their mind to hire your company. Plus, case studies can easily be incorporated into "drip campaigns."