When I travel between home and office now, I'm a lot more likely to take my iPad than a computer. Once I'm at the office, I generally rely on my laptop instead. It's an issue of convenience. When I'm out of the office, iPad is much lighter, and I can connect to my office pc remotely and enjoy "wire speed" access from it while it sits on the office network.
There are some things that an iPad isn't very good at, but for the most part it works pretty well. What surprises me is that despite Apple having been the first vendor to market with a viable tablet computer, there are still folks who try to berate the iPad as an overgrown smart phone. It may be, however that's part of the genius. By basing the device on the iPhone, the app store and the iTunes model came with it. The software for these devices runs much better on a custom phone OS than it would with, say, Windows 7.
Since its release, the iPad has generated over two billion dollars in revenue in a virtually uncharted market space. It's closest, most likely rival isn't due to arrive on the scene in the United States until November. By then, Notion Ink's Adam will have a very difficult time catching up.