Edward Tufte’s commentary on the iPhone interface is short, simple and to the point. He delivers a convicting summation at the end of the talk:
Here’s the general theory: to clarify, add detail. Imagine that. To clarify, add detail. And clutter and overload are not an attribute of information. They are failures of design. If the information is in chaos, do not start throwing out the information, instead fix the design.
This quote is key because it drives home the point that the information is the heart of the tool. You cannot sacrifice the information for anything. The design should not just adorn information, it should accentuate it, reinforce the message, and improve usability, not hender it. This advice is classic for all design, UI or not.