Sure, Tonya and I were waiting impatiently for the UPS guy to deliver our iPad on Saturday, and as soon as we got it inside, we opened it up, connected it to a Mac, synced some apps and media to it, and started playing. We even took turns and didn't squabble about who got to do what. That's how you can tell we're adults.

(As an aside, I want to take a brief moment to thank long-time TidBITS reader Eolake Stobblehouse, who sponsored iPads for the entire TidBITS staff as a way of encouraging us to cover this new platform. Eolake's generosity is unprecedented, and we are all tremendously appreciative of his direct support of TidBITS in this fashion.)

But I don't want to tell you about our first few hours with the iPad. If you're following the iPad news, you've undoubtedly read the pre-release reviews from the likes of Walt Mossberg and David Pogue (upon whom Apple bestowed iPads before most other writers), watched an unboxing video (boring, since there isn't much in the box other than an iPad, its charging cable, and a power adapter), and followed the excited tweets of new iPad owners. Apple even announced that 300,000 iPads were sold on the first day, and iPad users downloaded over 1 million apps and over 250,000 books from the iBookstore during the first day. I can't add much to that at the moment.

No, what I want to tell you about is why the iPad is truly astonishing now, and why it's going to become all the more important in the future. With hindsight, I could perhaps have come up with these ideas before touching an iPad, but when Steve Jobs described it as "magical," he wasn't hyperbolizing (and if that's not a word, it should be).

Tonya and I weren't able to attend the iPad introduction event in January, so this was our first hands-on time with the iPad. Simply put, there is a certain magic to using the iPad that's nearly impossible to convey in words - you have to touch it to believe it. And that's key to why the iPad will be the future of computing, though even those words don't do justice to what I'm going to describe, now that "computing" is as much about games and socializing and hobbies as it is about using spreadsheets and databases and word processors.

Here's the thing that I've realized after using the iPad - it's a blank slate, a tabula rasa. With a computer, we talk about what it can do, what programs it can run, what peripherals can be connected to it. That's apt, since computers are general purpose devices - unlike ovens and vacuum cleaners - and can be programmed to do many different things. But no matter what application you run or peripheral you connect, you're still using a computer. To a certain extent that's because we've lived with computers for 30-plus years now - we know what they look like and what they can do.

The iPad is different in a subtle and special way. It's still a general purpose computer in a way that superficially similar devices like the Kindle are not. It can perform thousands of actions - nearly anything that has occurred to any competent programmer with a Mac and $99 for the iPhone Developer Program - while the Kindle can only display text and grayscale still images. The Kindle is a fancy piece of paper (and one that lacks many of the good aspects of paper), while the iPad is a computer, with all that implies. (For thoughts on the iPad from a developer, read Matt Neuburg's "The iPad: A Developer's Anti-Contrarian View," 5 April 2010.)

So what's the difference between a Mac and an iPad? It's that blank slate thing. No matter what you do on a Mac, the keyboard and mouse and window-based operating system make it impossible to ignore the fact that you're using a Mac, and it's often equally impossible to ignore the fact that you're using a particular program.

In contrast, the iPad becomes the app you're using. That's part of the magic. The hardware is so understated - it's just a screen, really - and because you manipulate objects and interface elements so smoothly and directly on the screen, the fact that you're using an iPad falls away. You're using the app, whatever it may be, and while you're doing so, the iPad is that app. Switch to another app and the iPad becomes that app. If that's not magic, I don't know what is.

For example, when you're using James Thomson's PCalc, the iPad becomes a super calculator. When you're using we-Envision's Art Authority, the iPad becomes a virtual art browser. When you're using the Netflix app, the iPad becomes a TV showing every movie and TV show Netflix can stream (at least when it works; one of three shows we tried failed for unexplained reasons). When you're using OmniGraffle, the iPad becomes a dedicated diagramming tool. Heck, Twitterrific on the iPad is more the embodiment of Twitter than Twitter's own Web site, and, amusingly, when you use Amazon's Kindle app, the iPad becomes a Kindle, or, to put it another way, a fancy piece of paper.

You might ask how this is different from the iPhone and iPod touch, and that's a good question, because the answers are different. The iPod touch is of course much more like the iPad than the iPhone is because, Stephen Colbert jokes notwithstanding, only the iPhone can make phone calls. But the iPod touch, cool as it is, doesn't become the current app in the same way because of its small size. The apps are so small and so many user interface compromises must be made that it's hard to forget you're using the iPod touch as a device. As our friend Ken Case of The Omni Group has said, size matters, which is why a swimming pool is not just a big bathtub.

And the iPhone? It is, first and foremost, a phone, and everyone knows it. No one can unlearn that fact, and thus, it's difficult to see the iPhone as anything else. It will always be a phone that can do other things. Couple that with the same size problem as the iPod touch faces and you can see that while the iPhone is indeed an amazing device that would have been science fiction a few years ago, it's one that we could have predicted based on knowing about computers and mobile phones.

So we're back to iPad as chameleon, morphing into whatever you want it to be. That's astonishing, but it also requires more imagination from customers. Switchers can justify buying a Mac because they can imagine how it works in comparison with a PC. iPhone buyers can justify the expense of an iPhone because they can imagine how it will be better than a normal mobile phone. And iPod touch buyers can, I believe, justify a purchase because they can imagine how it's like an iPhone, but without the phone, camera, and GPS. (Some iPod touch buyers see it more as a better PlayStation Portable handheld game device, I suspect.) In each case, there's an easy comparison.

The iPad faces a more difficult path. For the moment, it's not as good at email and Web browsing as a Mac. And Skype and other VoIP apps notwithstanding, it's not a phone like the iPhone. The type of people to whom it will most appeal, right now, are those who bought only the iPod touch, and while there are many millions of those people, will they feel the need to buy the iPad too?

Ironically, the feature that I initially thought would be a huge leg up for the iPad - its compatibility with most existing apps - is the most disappointing. That's because old apps that haven't been updated for the iPad can be viewed in 1x mode, where they show at the exact size of the iPod touch screen, or in 2x mode, where everything is scaled up to the iPad's screen size. In either case, the iPad's spell is broken with nearly every old app I tried - it was either awkwardly small or awkwardly bitmapped. Yes, the functionality was there, but at the moment, I'll bet that most people are not using an iPad instead of an iPhone or iPod touch, they're using it along with one, so replicating functionality isn't that important.

Luckily, I believe the physical existence of the iPad and the upcoming flood of iPad-savvy apps - remember, very few developers have been able to write iPad apps using anything but the iPad simulator - will help our imaginations learn to cope with its possibilities, and as more people grow accustomed to the idea, it will be easy to justify the purchase. Until then, there are a few situations where the iPad is utterly easy to justify.

In the near term, I cannot see anyone spending a few hundred dollars on a digital picture frame when a $499 iPad is shockingly better. (I'm sure we'll soon see a bunch of stands and wall hangers that help display the iPad in its full glory.) Why buy a Kindle DX for $489 when $10 more gets you an iPad that's far better in every way other than weight and reading in direct sunlight? The sales of portable DVD players will no doubt suffer, since the combination of an iPad and the iTunes Store is such an elegant solution to watching movies on the road. I'll even bet that the iPad starts to cannibalize iPod touch sales from those for whom the iPod touch's small size is not a benefit.

In the longer term, while few will replace a modern MacBook with an iPad, I believe families with desktop computers at home will seriously start to consider buying an iPad and keyboard for a child instead of a more-expensive MacBook. There will be a time and a place for a computer, and just as the laptops have become more popular than desktops (despite their compromises) because they fit our mobile lifestyles better, so too will the iPad (or its successors) start to replace the laptop in situations where a full-fledged laptop is overkill.

I also believe that families will buy one iPad at first, but fairly quickly add others, as contention for the device grows. It's not so much that one can't be shared physically, but that so many apps are personal, either in terms of storing your data (whether a document, a book, or even a location in a book) or connecting with a particular online account. With our iPad, Tonya and I have already butted heads briefly over Twitterrific; whose account should be logged in? It will only get worse, and we fully anticipate all of us having our own iPads within a few years.

So it's possible that the iPad won't change the world instantly, but as more people realize that it can be whatever they want, doing a better job than most single-purpose devices in the process, I think we'll see sales rise and Apple refine the iPad's hardware and software to create the ultimate blank slate that can meet ever more of our needs and desires.