A usability study confirms what many iPhone users already know: the touch-screen keypad is harder to use than a tactile QWERTY keypad on a Blackberry or Treo type of phone. This isn't just about the iPhone, of course -- the difficulty will haunt any touch-screen phone.

From the study by User Centric:

While iPhone owners made an average of 5.6 errors/message on their own phone, hard-key QWERTY owners made an average of 2.1 errors/message on their own phone, p < .01. iPhone owners also left an average of 2.6 errors/completed message created on the iPhone compared to an average of 0.8 errors/completed message left by hard-key QWERTY phone owners on their own phone.

Some people, however, have figured out the typing thing just fine...

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