Underlying this entire process is the magic that you're bringing to the product. You are the person with the subject matter expertise and the customer relationships. Only you can provide the guidance that is needed to make your product great. You'll be looking after sales and marketing and making the key decisions about how your product is going to look.
We produce our best work when our customer is involved with the development process on an ongoing basis. The key to success in the agile development process is ensuring that we are delivering value to your customers frequently and incorporating feedback from them into any further changes. This can only be achieved if you are talking to your customers and using these conversations to drive positive change in your product.