"I like this, I don't like that." So what? That's just your taste. Yes, that's a starting point, but everyone overestimates how much they understand *other* users.. What you have to do is observe users working with the software for real. And you can't just do it for five minutes and declare yourself an expert; you've got to watch users over the course of years before certain things become clear.
I was for many years a software designer targeting PalmOS and later PocketPC. In the early days we designed what were essentially scaled down desktop applications -- using common sense of course. But unlike many people in the modern App Store environment I had close contact with users. I traveled to user sites to install the software and train the users. I rode in their trucks and watched them using the software in the field. And over the years I began to gain insight into the PDA form factor and how people use it. We all started out with the notion that UI design for handhelds was about dealing with the limitations of a small screen. It took me years to realize that mobile US design was actually about exploiting the potentials of a touch screen you held in your hand. When the iPhone came out I immediately knew that Apple got it: the handheld form factor is about the experience of direct manipulation. By using a capacitive touch screen Apple removed the last perceived intermediary between the user and the things on scree: the stylus.
Now I'm no longer a professional developer, but I do watch how people use their mobile devices with interest. The author is obviously right when he says a tablet is a different animal than a smartphone, but I think he hasn't grasped what the difference is. It's not just about screen real estate; it's about the totality of how the user interactrs with the device. You can't put a tablet in your pocket, and I think that's a much huger difference than it sounds; it stands for a whole lot of other things that are different betwen a palmtop device and one that is simply hand-holdable. For example he likes the idea of widgets that float over the active application as a way of making use of wasted screen real estate. This is technology focused design thinking (how can we use this resource), not user focused. And my admittedly casual observations suggest that this idea is bad for a lot of the way users use tablets.
One interesting development has been the near-disappearnce of handheld computers in the 4-5 inch screen range that *aren't* smartphones. But wi-fi only tablets remain popular. Why should that be? Again I haven't been observing as a developer, but I think it's because people have different application focuses when they use different devices. When you see someone using a smartphone as a computer they're texting, tweeting,instagramming etc. When they're on their tablets they're surfing the web, watching videos, reading ebooks, and playing games. The idea of widgets floating over active content is ideal for someone who uses their tablet like a smartphone. It's not so great for people using tablets in the ways they seem to. Of course some peoiple *do* use their tablets like smartphones. They're the people who drag out their iPad to take a candid photo. Such people exist, we've all seen them, but it doesn't make them typical. I'd guess most tablet owners these days also have a smartphone.
I'm no longer developing, so take this with a grain of salt, but it seems to me that the focus of smartphone use is connecting, the focus of tablet use is consuming, and the focus of desktop use probably should be creating. Blowing up a phone app to a 10.1 inch screen will clearly make it look ridiculous, but it may not matter. What matters is the usability of apps that are built for the things tablet users are focused on.