Thursday's announcement by J.D. Power was the iPhone's fifth consecutive win in the firm's semi-annual ratings.
Apple scored 795 out of a possible 1,000 points in the customer satisfaction survey, leading the two closest rival makers, Motorola (with 763), and HTC (762). Although Apple's score was slightly lower than in last September's survey, its margin of victory was greater.
Last year, the iPhone beat Motorola and HTC by 9 and 19 points, respectively; the newest survey put Apple ahead of those rivals by 22 and 23 points.
"It really is Apple, and then the next tier," said Kirk Parsons, J .D. Power's senior director of wireless services. Parsons attributed the larger gap between Apple and rivals to the release of the iPhone 4 last summer, and the relative lack of new models from Motorola and HTC in the second half of 2010, when J.D. Power conducted its survey.
"The iPhone just keeps getting better," said Parsons. "Apple keeps upping the ante by finding something, one key feature or a design change, to separate it from the rest."
The industry average for smartphone satisfaction was 761.
Although J.D. Power did not single out any specific model made by Motorola or HTC, both companies have bet heavily on smartphones that run Google's Android mobile operating system. Motorola's best-selling smartphones include the Droid and Droid X, while HTC's most popular models include the EVO 4G and the Inspire.
Yesterday, HTC launched the Thunderbolt, the first smartphone to run on Verizon's LTE network.
J.D. Power measured customer satisfaction by
weighting five question categories, giving prominence to ease of operation and the smartphone's operating system -- the former worth 28% of the final score, the latter 26% -- and discounting battery functionality to just 8% of the final score.
In J.D. Power's calculations, the phone's physical design accounted for 23% of the score, while features contributed 19%.
As was the case last September, the battery category was the only one of the five that Apple did not ace. It received just two out of five stars in the battery class, significantly behind leader Nokia, with five, and RIM's BlackBerry, with four stars.
The iPhone leads all others in the most-heavily-weighted category of ease of use, said Parsons. "Intuitiveness of the UI [user interface], Apple has that," he said.
J.D. Power polled nearly 7,300 U.S. smartphone owners, both consumers and business users, to come up with its rankings.
According to Parsons, satisfaction ratings were higher across the board when owners who use their devices to access social networking services -- Facebook, LinkedIn and Twitter -- were separated from the pack. The average satisfaction score from smartphone users who access social networking sites was 22 points higher than the overall average.
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