They won't pull many serious athletes away from Garmin et al until they add a lap button. We've had lots of laughs at our Apple Watch wearing friend who tries to remember his splits on the track since it doesn't have the convenience of a lap button. He also tells stories about having to use dead leaves to attempt to pause his run since his fingers were too cold/wet/something to register on the touchscreen.

No shopping cart discussion would be complete without mentioning Ideo. They designed a shopping cart for an ABC News broadcast. They are very much a company that works hard to understand value. When I grow up, I want to work at Ideo.

Link to a clip of the show:
http://www.ideo.com/media/info.asp?x=3