Chicago-based usability consultancy User Centric, Inc. compared texting on the iPhone with phones sporting a QWERTY keyboard.
It took QWERTY users almost twice as long to create the same message on the iPhone as it did on their QWERTY phone. "For QWERTY users, texting was fast and accurate. But when they switched to the iPhone, they were frustrated with the touch sensitive keyboard," said Jen Allen, Usability Specialist, User Centric.
Details of the iPhone texting usability study can be found here.