With the release of Research In Motion's BlackBerry PlayBook tablet less than a week away, early reviews say the PlayBook is, while physically impressive, clearly unfinished. But RIM isn't the only company to ship a tablet that feels like it could use more time in the shop.

The PlayBook lacks a number of seemingly essential features common to competitors, including a native web browser, email client, significant app support, and, (inexplicably) its own BlackBerry messenger. While RIM makes much of that missing functionally available via BlackBerry Bridge, the lack of built-in support for the features is, as one reviewer put it, absurd.

But the PlayBook does show promise. I recommend waiting on the PlayBook until more independently usable versions with the promised additions are available, concluded New York Times writer David Pogue. Wall Street Journal writer Walt Mossberg echoed that view. Even though Bridge is a neat technical feat, it makes the PlayBook a companion to a BlackBerry phone rather than a fully independent device, he wrote.

The general conclusion seems to be that, while the PlayBook is an impressive device, its lack of essential features makes it hard to justify buying it -- yet. RIM has to complete it first.

But all of that underscores something common to many device makers. They are all, at launch, unfinished, awaiting upgrades that often come months later. 

The early reactions to the PlayBook strongly resemble those of Motorola's Xoom, released in February. As with the PlayBook, the Xoom was shipped without major parts of its functionality included. This marred early reviews for the device, which Motorola clearly aimed to release prior to Apple's iPad 2.

One omission was Flash support, which didn't make it to the Xoom until March, when Motorola released a beta version of the software. Similarly. the Xoom's MicroSD card was inactive upon the device's launch, though some Xoom users have managed to unlock the functionality via some adjustments to the device's software. 

The Xoom, however, was in some senses worse than the PlayBook because some of its omissions were hardware-related. While the device was intended to be compatible with Verizon's 4G LTE network, the Xoom did not launch with the wireless radio capable of making that compatibility possible. To land the feature, Xoom owners have had to ship their devices to Motorola, which installs the radios before shipping them back. The process, Motorola says, takes up to six days. 

Nintendo played a similar game the the release of the 3DS, its latest console. While Nintendo hyped the 3DS's digital games store, internet browser, and 3D movies support in its initial announcement, those features were not available in newly-purchased devices. Instead, Nintendo released the functionality via a firmware update three days before the 3DS's North American release.

But unlike the 3DS, both the PlayBook and Xoom are direct competitors to Apple's iPad -- a factor that no doubt influenced the rapid and perhaps premature rollouts. With much of the devices' capabilities in software, companies like RIM, Motorola and Nintendo are able to make improvements to their devices long after customers take them off the shelves. That is one reason why buying a device at launch is becoming less of a good idea, and many consumers are waiting before they put money down.