People in a Chicago store look at the new iPad from Apple Inc. (Paul Beaty/Associated Press)

Apple Inc. began selling its much-anticipated iPad on Saturday in the United States, drawing eager customers intent on being among the first owners of a new class of tablet-style computers.

Apple must convince people who already have smart phones, laptops, e-book readers, set-top boxes and home broadband connections that they need another device that serves many of the same purposes. But the scores of people who waited in long lines across the U.S. on Saturday seemed willing to buy first and discover all its uses later.

Beth Goza has had iPhones and other smart phones, along with a MacBook Air laptop, yet she believes the iPad has a place in her digital lineup. She likened it to a professional tennis player owning different sneakers for grass, clay and concrete courts.

"At the end of the day, you can get by with one or the other," she said outside an Apple store in Seattle's University Village mall. But she's already dreaming up specific uses for her iPad, such as knitting applications to help her keep track of her place in a complicated pattern.

Danita Shneidman, a woman in her 60s, said she isn't particularly tech-savvy, yet she already knows what she's going to use the iPad for — looking at photos and videos of her first grandchild, born this week in Boston.

The iPad is essentially a much larger version of Apple's popular iPhone, without the calling capabilities. The new device is a little more than a centimetre thick, weighs 680 grams and has a touch screen that measures 24 centimetres inches on the diagonal — nearly three times the iPhone's. Also like the iPhone, it has no physical keyboard.

For now, Apple is selling versions of the iPad that can only connect to the internet via wireless networks. Those models start at $499 US. Versions that also have a cellular data connection will be available by the end of the month. They will weigh 730 grams and cost $130 US more, with the most expensive at $829 US.

In Apple stores in Seattle and on New York's Fifth Avenue, the atmosphere was festive, with employees cheering and clapping as customers entered and left.

Device has skeptics

Once the initial iPad excitement settles, though, Apple may have to work harder to persuade a broader swath of people to buy one. Other companies, such as Compaq, have tried selling tablet computers before, but none caught on with mainstream consumers. And while early adopters who pre-ordered an iPad in recent weeks have gushed about all the ways they hope to use it, skeptics point to all the ways the iPad comes up short.

They argue the on-screen keyboard is hard to use and complain that it lacks a camera and ports for media storage cards and USB devices such as printers. They also bemoan the iPad's inability to play Flash video, which means many websites with embedded video clips will look broken to web surfers using Apple's Safari browser. And the iPad can't run more than one program at a time, which even fans hope will change one day soon.

The iPad won't be available in Canada until the end of April, giving Canadians a few more weeks to gauge whether the devices really are the next big thing.