Tablet devices suddenly have emerged as a hot spot in the mobile device market. We might quibble about the extent to which tablets represent a brand-new category of devices, and the extent to which they will cannibalize existing categories. Probably there is some element of both, at the moment.

Early buyers of the Apple (News - Alert) iPad likely will not be typical mainstream buyers, however. Until now, the iPad has been a status symbol and novelty bought by users for whom the price is not too big a deal. To the extent that media tablets become a permanent part of the computing and mobile devices landscape, though, they will have to maintain a unique purpose and role in a users' life. Status value alone will not move the broader mass market. 

On that score, it now is not so clear how tablet computers will fare in the broad mass market, and what will drive their decisions, Steve Costello, GSMA content editor, argues. 

"In many use cases, it is not a particularly onerous task to come up with an alternative that would be better suited, often by being more focused on the task at hand," said Costello. To succeed, beyond the early-adopter segment, will require a clear value proposition for users who are not buying for the same reason as early buyers.

Gartner (News - Alert) suggests that some of the growth will come from the cannibalization of other consumer electronics devices, such as e-readers, gaming devices and media players. That's undoubtedly correct.

Still, dedicated devices typical can do a particular task more effectively, often can do those things cheaper, and in many cases are easier to carry around. E-readers, smartphones and notebook PCs all are examples of devices optimized for a lead application, and arguably perform those tasks better than, or at least no worse than, a tablet device, and in some cases also have the advantage of smaller size, meaning they are more portable, fitting into a backpack, briefcase, pocket or purse. 

Tablets can handle many of the tasks other devices support, to be sure. But tablets excel as "content consumption" devices, in some sense competing most directly with e-readers, but with the disadvantage of significantly-higher price, if the desired media to be consumed involves books and other text material. 

The deficiencies arguably are most obvious when comparing notebooks or netbooks with tablets. External keyboards will be available for tablets, which will ease text entry chores. Presumably, support for other peripherals will be available in the future as well. At some point, the external keyboards and other input and output devices will help, but only point out that a standard notebook might work better, and cost less. Then there is the matter of application support. 

Tablets also overlap to an extent with full-featured smartphones as well. For mobile e-mail use and light Web surfing, most smartphones will do a more than adequate job. Until data plans are available that support multiple devices, the additional cost of a 3G or 4G broadband connection also is an issue. 

WiFi (News - Alert) tablets will have their place. Apple iPod Touch devices seem to have found a niche, for example. Since the tablet ideally represents a new device category, users have to make decisions about carrying one more device. Some users already do so, of course. A user might carry both a phone and one or more additional devices when traveling. Many might carry a phone, a PC and a Kindle (or DVD player or iPod). 

It isn't so clear the typical user carries a tablet and a phone when out and about locally. Of course, that also applies to notebook PCs. Most people, most of the time, do not carry anything but a mobile phone when out and about locally. 

For that reason, and because most tablets are WiFi-only devices, many believe the tablet will become a living room item that is used in a shared way by family members, much the same way a TV is used, but not seen as a "personal" device. 

Late in 2008, it was the netbook computer that seemed to be the next big thing in the PC world, offering low-cost, Internet-focused computing in a more-mobile format. There's now some dispute about how big a trend that will be.

For the moment, many will continue to see the tablet as an additional device that ultimately will supplement existing devices and usage modes, rather than fully replacing any of them. There's no question the iPad has a good market as a prestige item that actually doesn't have to replace any of the other devices people use. They get carried to meetings where the user does not expect to have to do too much. Back at a desk, it's just easier to use a PC for all the other things people normally do at work. 

In a home setting, tablets are more convenient for any light browsing or messaging that might be useful when watching TV. Maybe people will find some new use case that justified the investment. Right now, it might be hard to argue that a full-featured smartphone or netbook can't do all the things a tablet does, in casual mode. 

Right now, one might argue a tablet is an expensive way to do things you already can do on devices you already own.