"Sorry, I don't understand."

Too often, that's the response my wife gets from Siri when she asks "her" a question. She's mostly given up trying. And you know what? My wife isn't alone. No less than Apple (Nasdaq: AAPL) co-founder Steve Wozniak is unimpressed by the company's soon-to-be omnipresent voice assistant.

"A lot of people say Siri. I say poo-poo," Wozniak said in an interview with the Times Union newspaper in upstate New York.

Really, Woz? Siri is so bad that you've got to reach back to playground days for an apt descriptor? Ouch.

But it gets worse. In the interview, Woz described, in detail, how he used Siri to make reservations, divine the largest prime numbers, and find the largest lakes in California, among other things, before Apple purchased the software in 2010. Each time, Siri would perform flawlessly, Woz said.

And after Apple took over? Woz said Siri would return results that were either unrelated or irrelevant. "I'm really disappointed, but it's still a market for the future," he said.

Woz's comments reflect a different level of frustration than my wife experiences. She's never had success with Siri; Woz did, at one point, but apparently doesn't any longer.

The worry for investors is that Siri is key to Apple's long-term strategy. No longer merely confined to the iPhone, the cheeky voice assistant is moving to the iPad. OpenTable's (Nasdaq: OPEN) reservations system, and Time Warner's Rotten Tomatoes movie review aggregator, are also being redesigned to take advantage of Siri. So is Twitter. All signs point to Apple viewing Siri as its next great computing interface, much in the same way that Microsoft (Nasdaq: MSFT) changed gaming interfaces with its Kinect hands-free controller.  

Woz's comments suggest that he envisions a similar opportunity -- e.g., it's a "market for the future" -- one that could set iDevices apart in the eyes of consumers who have plenty of options, thanks to good work by Google (Nasdaq: GOOG), whose Android operating system is now the world's top choice for new smart devices, and Microsoft, whose Windows Phone is slowly gaining acceptance.

But for Apple to take full advantage of the mobile revolution, Siri is going to have to lose the stink that has Woz turning up his nose.

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