“Form follows function” is a classic design principle, and is generally accepted as an axiom. However, the iPad that geeks the world over have been fiending for is an outstanding example of the opposite, with function following form. Computing in general does tend to throw "form follows function" out the window (on the physical end) as much of the functionality comes from software, but nothing really shows how often it is functionality that needs to do the following like the iPad and tablet computers.

Robert Scoble has a good post on the uninspiring tablet demos by Steve Ballmer and how the tablets shown have generally missed the mark. Other tablets have tried to force the mouse & keyboard-based interface and experience on the tablet form. This is the biggest mistake those tablet makers have made, and the primary reason for tablets not catching on yet. You don't try to use the same UI and duplicate the mouse & keyboard experience, or make up for the lack of it, in a form-factor that doesn't have either. Instead, you make it different, so the mouse & keyboard are not even needed; design the interface around the primary input method, fingers! There's a reason the software used by John Anderton didn't have a start menu.

Gizmodo has an article that makes the case for the iPhone OS on the Apple tablet, and it describes how the iPhone paved the way for the iPad by establishing a computing interface that only needed multi-touch. This emphasis on the touch experience is highlighted by the statements made by Steve Jobs during the presentation. He said there are millions of people who already know how to use the iPad, those with iPhones or iPod Touches. Apple is taking advantage of the familiarity with the touch experience it has established to ease in users to what is a relatively new form for many. They did the same sort of easing when the iPhone was first coming out and getting apps. Calling it OS X then helped people understand that it's not just a phone, it's a computing device. It's not actually the same as Mac OS X, and this comparison has largely disappeared from Apple's marketing language, but the comparison is perfectly appropriate.

The Gizmodo article also talks about the prior failures of Windows in the tablet world. The idea behind the tablet form was right, but the ideas of the functionality it would have were wrong. In his post, Scoble highlights a variety of use cases that were not addressed by Ballmer during his presentation. Ballmer couldn't address any of those use cases, because the tablets were trying to replicate the full desktop experience where it doesn't make sense. Sure, Windows 7 has some nifty touch features, but nobody wants it on a tablet-only device — as opposed to a convertible tablet/laptop — because it doesn't belong there. Many people may say they want Mac OS X in a tablet form, and there is nothing stopping them from buying just that. But when it comes down to it, that interface combination of desktop GUI and tablet input only makes sense for a relatively tiny niche of applications . (Also, many of the complaints about the iPad are from people who haven't even tried it yet, or for some not even the iPhone/iPod Touch. You can't judge interfaces and experiences by proxy-experience.)

Physical form follows those needs and use cases, but the functionality has to follow the form. Until now, this was largely missing from tablets. Interestingly, the Microsoft Courier does a more intriguing job of reinterpreting the tablet form-factor than the iPad. If the Courier is anything like its concept video (and I hope so because I really, really want one), both it and the iPad will usher in an era of function following form. All this being said, I would love to have a touch-based monitor for my desktop systems like the Cintiq, but it won't be much more than a supplemental specialty interface until the functionality through software follows the form of the tablet.

Fortunately Microsoft, or at least the arm involved in the Courier, seems to agree with the need for a fundamentally different UI scheme on ZDNet: “The original Microsoft Tablets ‘failed because the applications were not tailored to a tablet form factor - that is, Word still had toolbars and menus and scollbars. So, a tablet needs to be like an iPhone - a UX that is specific for the form factor,’ the source said.”