Overall I thought the premise of the letter rang very true.
As far as using them in the classroom? I actually have a student who owns one and uses it around school I think more than the netbook that she was issued. I don't honestly believe they are any better/or worse than the netbook on writing papers. The Dell netbooks that our school bought last year are terrible to the point of being unusable without an external mouse. The screen on the iPad + thinness really makes it better on that point. An external bluetooth keyboard in theory could make it as useable as the netbook.
My biggest concerns about passing out iPads to kids though are the costs of replacement screens. As it is the netbooks this year have been dying at a higher rate than the first year (dropped, stepped on, etc.) The iPad 2 screens in particular are not supposed to be cheap if I remember correctly. The flip side though, is that if people would start allowing students to access their textbooks from them - and be able to annotate on them - it might be better there. Most of the time though our teachers are so locked into this curriculum system (C-SCOPE) that I don't even know how much they use their textbooks. They use a lot of materials from there that could be just as easily shared via PDF on iPads.
For me I love the device. It's great for so many things, and I love the flexibility to have music scores - and hopefully marching drill this year - on it.
If you're into music at all check out some of his compositions. I'm a band person (director), but his choral stuff is amazing. He's also transcribed many of his pieces (including this one) into band works and written a number of orchestral pieces. (October is by far my favorite)
1 + 1 = 3, for large values of 1.