The iPad can't quite be your only computer, because you need a machine running Mac OS X or Windows to set it up and install software updates. And yet this device's size, weight and inability to make phone calls preclude it from replacing a smartphone.
Instead, you need an opening between those gadgets, a vacancy that might otherwise be occupied by a netbook or electronic-book reader.
Many other attempts to fill that gap have flopped; who now remembers Microsoft's "Smart Displays" and "Ultra-Mobile PC", for instance?
The iPad is light-years better than those doomed devices, but it's not "magical and revolutionary," either (to quote Apple's ad copy). A week with a $699, 64-gigabyte model lent by the Cupertino, Calif., company had both "ha!" and "huh?" moments.
No doubt, the iPad will dislodge some laptops from coffee tables and boot some e-book readers out of carry-on luggage. But that says as much about the sloppy design of many netbooks and the limited capabilities of e-readers such as Amazon's Kindle series and Barnes & Noble's Nook as it does about the iPad's virtues.
The first among them must be browsing the Web. This WiFi-enabled tablet's 9.7-inch touch screen and speedy processor provide an experience far superior to that on Apple's smaller devices. Pages snap into view as fast as they would on a desktop, and you rarely have to zoom out or scroll sideways to view their content.
Typing is easier when each on-screen key is the size of a grown-up's fingernail instead of a child's. With the iPad held sideways, it's even barely possible to touch-type. Or you can use a Bluetooth wireless keyboard.
But without Adobe's Flash software, the interactive content on many sites disappears on the iPad. This represents a bigger problem on this device than on the iPhone, where many sites automatically serve up mobile, Flash-free versions.
The iPad's larger size allows for outstanding battery life, although replacing its sealed-in-the-case battery will require professional service. With WiFi on and its screen set to stay illuminated, the review iPad lasted for almost 12 hours while playing music; leaving WiFi off added about half an hour.
For similar reasons, the iPad makes for a much better photo and video viewer than an iPhone or iPod Touch, helped by applications from ABC, Netflix and others that let you watch TV shows and movies from those sites.
(Then again, the iPad's iPod music software buries its shuffle-playback option so deeply that I had to look for it in the manual.)
The iPad will do even better in this role when a software update, due this fall, finally lets it run Web-radio programs while you do other things.
You'd think the iPad would be a great e-book reader, too, but its hardware sets it back. The screen lends a slight bluish tint to the white of an on-screen page, its glossy coating reflects the sun and other overhead lights, and at 1 1/2 pounds, it's too heavy to enjoy reading while standing up. In its favor, it can display colors and turn pages without a distracting pause, unlike the "e-ink" displays on the Kindle and its ilk.
Apple offers a new iBooks store for the iPad, but its selection falls short of Amazon's Kindle Store and its prices exceeded Amazon's in a few test cases. You can also run Amazon's Kindle software on the iPad or read electronic editions of some newspapers and magazines.
The iPad looks weakest as a productivity device. Although developers have shipped some creative applications for it the $10 iPad version of Apple's Pages looks downright pretty, a word I didn't think I'd use to describe a word processor sharing your work from the device is tricky, and printing it is impossible.
Forget the iPad's advertised compatibility with existing iPhone applications: They either run inside a small frame at the center of the screen or appear crudely magnified, with blurred type and graphics.
Buyers will want to hold out for iPad-compatible programs, noted with a plus symbol in the App Store. But they'll also have to hope that iPad developers, especially smaller ones, can survive the App Store approval process: This company has a history of rejecting or removing applications for poorly explained reasons and shows no signs of relenting.
Would-be buyers also have to worry about future versions of the iPad making today's look like the 1.0 release it is. For instance, mobile broadband-compatible models, at $130 extra, are due at the end of the month. (You'll be able to buy wireless access from AT&T, a month at a time, starting at $15.) But what if later on, Apple ships a lighter, paperback-size model?
Meanwhile, you can also expect, or perhaps just hope, that e-book and netbook vendors will step up their game.
The iPad may be the first good not great device to fill the gap between laptops and smartphones, but that doesn't mean it should be the first one you buy.