My team has just finished a video retrospective on mobile keypad usability
that you might find useful. Note: all usability tests were conducted in
the US on US-available handsets.
This year, I have presented the material at Cambridge Wireless, the London
Usability Professionals Association, and New York's Mobile Monday. The
video presentation is now available for purchase. Here's a shortened
description from our web site:
During Usable Products usability testing of mobile phones, we encountered
dozens of examples of keypad trouble: keypads and input devices on which
usability participants experienced undue difficulty completing tasks.
We gathered the best examples of the worst problems into a concise
presentation with video clips and written analysis demonstrating the
precise issues surrounding mobile keypad usability:
Frequent and infrequent key use
Back button implementations
Cramped button layouts
Flat or nearly flat keys
This presentation includes 20 brief clips (nearly seven minutes total
running time) and analysis in a PDF that is delivered on CD ROM. Keypad
Trouble is priced at $1,995. You can learn more about it from http://www.usableproducts.com/publications/keytrouble.shtml, where you can
view a sample page, thumbnails from the entire presentation, and download
a one-sheet and order formor even buy it directly from the site.