Long form writing seems close to impossible on a tablet. A long hacker news comment is possible, but once you are looking at even a modest book report, I can't see it.
Maybe with some sort of accessory keyboard, but then you are looking at more of an ad hoc laptop than a pure tablet.
You'd expect long-form writing to be unthinkable on today's mobiles, but plenty of people wrote whole novels on Palm PDAs with only the on-screen keyboard/Graffiti. I also performed extensive text entry on Palm PDAs for my middle/high school notes and assignments, and didn't consider it a bad experience. And these examples, and the above commenter with his Sim City clone for the TI-82, demonstrate, when you make up your mind that you're going to do something on a limited device, it's often surprisingly possible.
Maybe with some sort of accessory keyboard, but then you are looking at more of an ad hoc laptop than a pure tablet.