Via design.org: The UX Design Success Ladder: Achieving Meaningful Product Design.
Product success envisioned as rungs of a ladder, that you climb up from the bottom: functional, usable, comfortable, delightful, meaningful.
I first heard this concept last year at WordCamp Phoenix in a presentation by Ward Andrews; the article showcase examples of products or services at each level.
Takeaway message: don’t stop at functional and usable. Set the bar higher.
The Sensible Leader 