When you stake your future on a big touch screen, you've got to expect a lot of pushback.

Apple ( AAPL) isn't the first device maker to ditch -- some might say liberate -- the standard mechanical keyboard in favor of a virtual buttons. But the hotly anticipated iPhone, which is due to go on sale this evening across the nation, marks a make-or-break moment for the technology.

The touch screen opens up a whole new world of utility. Getting the phone's limited surface to serve double duty for input and viewing is brilliant in theory. But as any bank ATM user probably knows, this smudgy innovation can also serve up a whole heap of frustration.

"The biggest disappointment will probably be the virtual keyboard, at least for anyone used to a Treo, BlackBerry or Sidekick," says Peter Rojas, editorial director of tech blog Engadget.

Smartphone users who are avid emailers and texters have grown adept at using their mini keyboards and hugely dependent on them. These people might prove to be the iPhone's most vocal critics -- or at least the hardest crowd to please.

But just as computers eventually won the hearts of many diehard typewriter fans, the touch screen will finally win converts, say industry watchers.

"In the long run, the touchscreen will be a success. It's where the future is going," says Roger Entner of IAG Research. "The iPhone will be version 2.0 of touch screen. We'll have to wait to see how well it has been solved."

Apple's hallmark, he says, is its user-friendliness. "It's been the key to what Apple has done since the introduction of the Mac. But no one bats 1.000 -- not even Steve Jobs," says Entner.

Industry watchers say there is plenty of room for improvement when it comes to cell phones, and Apple's wizardry with gadgets -- Newton aside -- makes it a good candidate to take on the reinvention of the mobile phone.

It's hard "to guess before anyone's had a chance to spend some serious time with it, but it looks like they've probably nailed the integration of multimedia into the user experience," says Rojas.

This is something Nokia ( NOK), Sony Ericsson, Motorola ( MOT), etc., have all struggled to perfect," Rojas says.

Want more? Check out TheStreet.com TV video. Janet Al-Saad looks into the iPhone's 'fumble-fingers' effect.

To see other stocks that might benefit from Apple's big day -- including Marvell Technology (MRVL), Broadcom (BRCM) and Sony (SNE) -- please click here for a Stockpickr portfolio.

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