For your customers, your proposition (your product or service) is nothing more nor less than the experience it offers. Great user experience has its roots in product management (where it’s conceived), and its leaves in project management (where it’s delivered). But it also depends crucially on answering questions like these:
What’s the best concept to put at the heart of our product?
How do people really behave, and how can we take advantage of that?
How should we set ourselves up to create more usable products?
What’s working and what’s not working in an existing or proposed design?
How do we go about improving the interaction design of our products?