I tested both Apple's Keyboard Dock and several Bluetooth keyboards with the iPad, and they all worked well. The iPad supports keyboard shortcuts, so anyone who has trained themselves to hold down shift to and press the arrow keys to select text, then press command-X to cut the text and command-V to paste it somewhere else, will discover that those keys perform those very same tasks on the iPad. And the iPad is plenty responsive, even to a fast typist like myself--I never noticed it dropping any characters.
The Keyboard Dock works well if you're sitting at a desk, but in general I think more people will like typing with a Bluetooth keyboard like Apple's incredibly tiny Wireless Keyboard. (You'll just need to use a case, stand, or convenient box to prop up the iPad at a good angle for viewing while you type.)
iPad as reading device
One of the most talked-about aspects of the iPad is its potential as a reading device, most specifically as a competitor to e-book readers such as Amazon's Kindle and Barnes & Noble's Nook. There's also been quite a bit of conjecture about the iPad's ability to singlehandedly save, transform, or otherwise alter the downward trajectory of the magazine and newspaper publishing industries. (That's a lot of drama to pack into one little gadget!)
I've owned an Amazon Kindle 2 for a little over a year now, and I like it a lot. It's lightweight and its grayscale e-ink display is quite readable, albeit bland. The iPad is quite a bit heavier than the Kindle (think hardcover versus paperback, though that comparison isn't quite right), and its backlit LED display couldn't be more different. The Kindle fails in dark conditions, because it can't light itself--I actually bought a clip-on book light for mine. And of course, the iPad presents everything in glorious color.
I suspect many people expect the iPad to put the Kindle out to pasture, but I'm not entirely convinced. What the Kindle has going for it is its simplicity as a unitasker. The Kindle does one thing well: allow you to read books. (It also lets you read magazines and newspapers, though it does that a bit less well--but then again, Apple's iBooks app doesn't support magazines or newspapers at all.) It's cheaper than the iPad, and will presumably get cheaper still in the face of such stiff competition. If a friend or relative came to me and said that all they wanted was a book reader, nothing more, I would happily endorse the Kindle.
What the iPad offers is, quite simply, more. It's not a unitasker. It reads books, but it also surfs the Web. (The Kindle has a Web browser, but it's terrible.) It runs apps. Competing merely as an e-book reader, it's a tight race, but the iPad's boundaries go far past where the Kindle was ever intended to go.
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