The iPhone lived up to its hype in carefully conducted usability tests against the the Nokia N95 and an HTC Touch, according to Computerworld on Friday. Some testers couldn't even complete a phone call with the HTC Touch, a Windows Mobile device.

The HTC Touch isn't now available from U.S. carriers, but HTC still agreed to participate in the testing and said that it will be by the end of the year.

Perceptive Sciences conducted the test with ten people who had never used any of the three phones. Each was asked to perform a series of tasks, and their performance was based on measurable data, such as the time it took to complete the task. The overall theme of the test was to determine how easy it was to take the phone out of the box and start using it. Each phone was rated from 1 to 5 in several categories and also given an overall score 1 to 5.

"People can eventually learn to use any device," research scientist Tim Ballew said. "But that's not true usability. We wanted to see how long it took to figure out how to use the phones. That's the difference between learnability and usability."

The bottom line was that the iPhone blew away the competition. The iPhone scored 4.6, the HTC touch 3.4 and the Nokia 95 scored 3.2. Testers were about twice as fast doing any task on the iPhone compared to the others. Mr. Ballew reported that some of the testers had trouble making a simple phone call on the HTC Touch. "That's pretty basic functionality, but we had people who couldn't complete a call at all," he said.

In the functionality category, the N95 won, but the price paid was loss in usability. For example, testers were faster and more successful getting to a Web page with the iPhone. The conclusion was that there are tradeoffs between feature-richness and usability, and the iPhone clearly focused on usability, ergonomics, and navigation, wining easily in all those categories.