KDE seems to manage the jump between Desktop, Netbook and Tablet without much effort in the part of the apps. Adding a box with an X to close them is again hardly rocket science. I can take a current desktop linux app, even one not specifically developed with KDE in mind, fire it up in desktop mode, it have a border, fire it up again in netbook mode and the controls appear as part of the task bar at the top, in tablet mode the app borders and decorations are in a style that is more fitting with the form factor. Just a shame that KDE is basically windows with Downs.
This is available today.
On the Padfone again we see that the apps don't need special modifications to run in either mode - the underlying toolkit deals with that. Given that apps are designed to handle different resolutions anyway, it's hardly a massive jump. There is absolutely no need on the part of the app developer to worry about this as ICS does all the grunt work, just as in the KDE example. Any app written with ICS in mind should have no problems at all running in either tablet or phone format. At worst in the padfone example, you might have to restart some apps when you plug the phone into the tablet dock.
Go check out the reviews of the padfone on Youtube and see it in action, I saw one by a spanish reviewer about a month back and the apps, which were third party by and large, all seemed to cope well in either form factor. Unifying the codebase under ICS meant that there was no longer a need to write one version specifically for tablets and another for phones, just write for ICS and your bases are covered.
Is it for you? Based on what you've said probably not. Hell it's not even for me if I'm honest (frankly the cost is higher than a similarly specced smartphone and tablet). But the complaints you've put forth simply don't apply.
But, all that said, as practical implementations of the concept go, the padfone does seem to offer a fairly stable and usable base from which to go on.
Now if only they could make Android pleasant to type on, they might actually be able to turn it into something that right now is strictly usable only for content consumption into something capable of content creation...