Research In Motion's PlayBook (RIMM), the long-awaited response to Apple's iPad, went on sale in the United States and Canada on Tuesday in a launch RIM desperately hopes will win the hearts and minds of consumers.

But customers trickled in only slowly at stores that opened early to let customers grab a PlayBook on their way to work.

At a Sears department store in downtown Toronto, just five people showed up for the 7 a.m. opening, a stark contrast to the frenzies whipped up by an Apple (AAPL) product launch.

The stakes could not be higher for the Canadian company, whose BlackBerry smartphone once reigned supreme but which has struggled to compete since Apple's iPhone and a slew of devices running Google's Android (GOOG) entered the fray.

Reviews have panned the WiFi-only tablet computer for lacking RIM's trademark email and organizer applications -- it needs a BlackBerry or other smartphone to access those.

But retailers, including Staples (SPLS) and Best Buy (BBY), say solid pre-orders suggest pent-up demand for a capable alternative to the iPad.

"Some of the complaints they had don't really apply to me, like not having native calendar and email doesn't matter because I've got a BlackBerry and I'm going to have that everywhere," Andre Cousineau, a 34-year-old working in banking, said as he picked up the new device.

Some 20,000 stores across the United States and Canada were to stock the PlayBook at launch, and it will also be sold directly to enterprises.

Some say it is unfair to compare the newcomers to the iPad, which made the tablet market a reality last April. Apple sold almost 15 million iPads in 2010; RIM is expected to move 3 million PlayBooks in a similar window in 2011, according to 18 analysts polled by Reuters.

"It's not going to be in the same league as the iPad," said Al Hilwa, a Seattle-based analyst at IDC. "The question is will it sell more than the Xoom but less than the Galaxy," he added, referring to Android-based tablets from Motorola Mobility and Samsung.

Underscoring the challenges in creating the buzz typical of an Apple launch, Staples Canada ditched plans to open its doors at midnight in favor of a more sensible 7 a.m. start.

"We just think it'll make more sense for business customers to come in on their way to work," head of merchandising Pete Gibel said. "Midnight is more of a consumer play."

But analysts say the Playbook should stay in the hunt, even if it gets a slow start, as it overhauls its creaky platform with the QNX operating system it acquired last year.

Gartner, a research outfit focused on technology, estimates one in 10 touchscreen devices sold in 2015, or some 30 million, will be powered by QNX, which will likely also find its way onto its smartphones in the next 12 months.

That would place it third behind Apple at almost half the market and Android at just under 40 percent, leaving little room for Hewlett-Packard's (HPQ) soon-to-launch WebOS tablet and completely ignoring a possible Windows tablet platform.

In its current setup, the PlayBook's prime audiences are the 60 million-odd active BlackBerry users worldwide and corporate IT managers who use the BlackBerry for sensitive corporate data. RIM expects large businesses to buy shipments in "the tens of thousands."

Cellular-connected PlayBooks are due out mid-year.

For the child in every user, RIM has stolen a sheet out of the iPad's playbook, teaming up with Electronic Arts (ERTS) to ship its tablet with the car-racing game 'Need For Speed: Undercover'.