The web has matured to a point where a lot of UI problems have been solved. If possible we should avoid using new, unproven patterns in design that add cognitive load on the user.
Slow products and services can be the result of poor design. A well designed experience should be efficient and solve a user’s needs as fast as possible.
Good design should seek to remove barriers and reduce complexity where it is not needed. Good design is boiling down an experience down to it’s bare essentials.
A well designed product should be approachable and available to as many users as possible.
Human beings are emotional creatures. Well designed products and services should be aesthetically pleasing and seek to generate a positive emotional response from the user.