You can tell when an object is well-designed. It feels solid in your hand. The cold of aluminum or steel. The subtle grain of real wood hand-chosen for its beauty and strength. Leather that won't degrade over time. Well-designed products are defined by their function and usefulness, but are also beautiful enough to leave out on a table.
Digital products are different. You rely on your eyes alone to tell you everything about how a product works. Software lets makers like me do anything — and that's both a blessing and a curse. We designers must practice extreme discipline to successfully craft products that are useful, simple, and bring delight to our customers.