Conventionally, product requirements are gathered by soliciting users for requirements. If the user is solicited for requirements, he will only be able to come up with some imaginative thoughts, but those might not necessarily be his real requirements.
Instead, give user a pilot product to use. Now you may ask how do you come up with a pilot product. Its a catch-22. Here is where you will be creating your differentiation or creating a new market altogether. You have to become a keen observer of the problem that you are trying to solve. Once you have intricate knowledge of the problem space, you can start to answer that by your pilot product. It is this pilot product that you provide to your users. Once the user has a tangible pilot product to play with, he will be able to point out shortcomings. Real requirements will only surface when he will be provided something tangible to play with. Here you should tap into the basic nature of us humans and that is we are experts at pointing out negatives in any walks of life. Give the user your prototype product, and he will easily be able to come up with a laundry list of shortcomings in your product. These shortcomings are your product's real requirements.
