The Impetuous Manifesto
Ideology Behind the Manifesto
Handheld devices should not be thought of simply as 'small desktop computers'; This is the approach to mobile devices which Microsoft has mainly employed. PDA's should work for you, not the other way around, which is sadly very often exactly the way it works.
The Failings of Smartphones
Many believe that, with the emergence of smartphones, mobile phones with cameras, and the like, that by the end of the current decade, PDA's will cease to exist as standalone devices. What this very-prevalent view fails to acknowledge is the fact that all mobile devices on a carrier's network are controlled by that carrier. Mobile carriers are more interested in having new product to push at oneself, ever year or two when one's contract expires. This is a severe conflict of interest.
There are many inherent problems with smart-phones; It is extremely difficult to have any kind of useful human interface with a device which needs to fit in one's pocket. Entering an appointment or meeting into one's non-stylus-driven smart-phone ends up taking an immense amount of time, as even with T9 predictive text input, it's very cumbersome to enter any quantity of information. The buttons on such phones are also typically extremely small and difficult to hit accurately.
Since your mobile carrier controls the phone, they may decide, at any time, to transition away from one air interface, such as GSM, to another, such as W-CDMA. This transition has already happened once in the data-age, where, around 2002-2003, many mobile networks shut off and transitioned their legacy TDMA networks to GSM. When this occurrs, you can be left with a very expensive brick.
Additionally the conflict of having a phone be the primary device you store information with causes an inherent conflict; if you are on the phone exchanging information with someone else, it is impractical to be storing notes in the phone, or writing emails you are talking a.bout
Every major mobile carrier in the US has at least one "free" phone (with contract) which includes Bluetooth. This is a new development, and is notable because any mobile device is then capable of accessing the Internet via Bluetooth.
The failings of the Apple Newton
The newton existed in an era before Wi-Fi even existed, and even longer before it was ubiquitous to the extent it has become today. Proprietary radiomodem networks such as Ricochet Communications' networks attempted to fill this wireless communications void, but were slow, proprietary, and relatively expensive. This severely hampered the real-world usefulness of the device. Getting online was pretty much limited to dial-up modems, and the Internet was still in its infancy, as a non-academic network, in 1993, when the first Newton PDA was released.
The Failings of PalmOS
Palm OS was developed out of hindsight from the Newton. The design of PalmOS appears to have come from the idea that the Newton was a failure.
While graffiti was an interesting concept for handwriting recognition, it was also an unnatural stop gap. The user was forced to learn a new script to write in and was also made to write all their letters in the same place, fighting the natural instinct to write letters linearly.