Storage. Dunlap is correct that the largest storage capacity available on an iPad or iPad 2 is 64GB, and that most notebooks have at least 250GB of hard drive storage. No argument there. Dunlap goes on, though, to talk about the virtues of storing massive amounts of movies, TV shows, and music on a laptop. A 64GB iPad has enough capacity for five or six HD-quality movies, with enough left over to store thousands of songs, and a virtual library of books in the Kindle app. How much media do you need to carry with you, exactly?
Besides, you can pull up headlines almost any day of the week about data breaches that have resulted from a laptop being lost or stolen with hundreds of gigabytes of sensitive data on it. Storing data in the cloud using services like Box.net or Dropbox means that A) you can access it anywhere and anytime as long as you have a device that can connect to the Web, and B) that if your device that connects to the Web gets lost or stolen, the data is still safe in the cloud.
Battery Life. Dunlap cites the lack of a swappable battery as a handicap for the iPad. I see the need for a swappable battery as a weakness for his ThinkPad. Dunlap is concerned that if you need to work on a long plane ride and/or in a coffee shop and there are no available outlets, the ability to swap batteries will be crucial.
Well, when you're talking about a notebook that gets two to three hours at best from its battery, I can see why you need a backup plan. So, now you're talking about carrying your notebook that weighs two and a half pounds more than the iPad, plus an additional battery--which by itself weighs as much or more than the iPad--just so you can get a combined battery life that is only 40 to 60 percent of what the iPad provides in the first place.
My comparison only really looks at the iPad (or iPad 2) compared with the Lenovo ThinkPad, as Dunlap's did. But, the Apple iPad is no longer the only tablet game in town, and other tablets change the comparison in many ways. Other tablets like the Motorola Xoom or Samsung Galaxy Tab line have microSD slots for expanded storage capacity, USB connectivity, compatibility with Adobe Flash, and other features that PC enthusiasts may find lacking in the iPad.
The tablet is clearly the superior mobile computing platform for all but very specific, hard core usage scenarios. You can cling to the notebook if you choose, but your days are numbered. Resistance is futile.