Sometimes, a simple shift in metaphor i.e. Hipmunk's gantt chart is enough to substantially improve the UX, but sometimes it requires an entirely new product strategy to do something revolutionary. Consider Amazon Prime. Is the user interface particularly pretty? No, but the experience of using the service truly is revolutionary, and so far no other retailers can match it because the experience is only made possible by supply chain management and distribution that Amazon has in place.
The iPhone UX was revolutionary because it challenged the entire model of interaction between user and phone. The experience of using an iPhone is the sum total of an astounding number of innovations, only some of which have to do with the UI. Consider the hardware innovations from the glass screen to the proximity sensor, to the hi-res screen in the iPhone 4 that no one expected or anticipated. Then there is the ecosystem aspect, which required not only a fundamental re-thinking about how both users and developers would interact with technology, but also massive distribution which was already in place through iTunes. Of course, the multi-touch interface, and the laser focus on developing quality software for email, messaging, phone, and music, played a huge role in overall UX, but they would not have been possible without the other innovations.
I guess it really all just goes back to the fact that design is how it works, not how it looks, which requires a deep understanding of the problem and needs of the customer, not just the ability to arrange pixels in a pretty pattern on the screen.