Battery life: Apple says iPad provides 10 hours of battery life and, as others have noted, it will likely actually give you more than that. After four hours, our iPad still registered 70 percent battery life with audio running in the background the entire time. It was also used for word processing, its GPS/mapping was tried out, and other testing was performed. Unlike the iPhone, though, iPad tells you what percent of battery life you actually have remaining so you can manage power use easier. Battery life here is a competitive strength not a weakness.
The keyboard: After two minutes, you might hate it. After five minutes, though, you could start loving it. This review is being typed on iPad using Apple's $9.99 Pages app, which has been optimized for iPad. Once you get the feel of it, even power typers like the one writing this review will find it easy and comfortable to use. (Full disclosure: this is being written in landscape mode, where the keyboard is larger and wider.)
Performance: Apple is using a 1.00 GHz A4 processor for iPad—its own, proprietary CPU. That was a roll of the dice on Apple's part, but it seems to have paid off. The device boots fast, runs fast, is exceptionally cool to the touch after a couple of hours of use and, as mentioned, gets great battery life. That can't be an accident. While Intel has done ground-breaking work on developing and engineering the Atom platform, from this vantage point it appears that Apple has either caught Intel or surpassed it on mobile CPU technology. (Extensive, head-to-head benchmarking between A4 and Atom will need to confirm this, though.) For now, just know that Apple is sitting on powerful processing technology that will deeply impact the industry, it seems, for much time to come.
Mail and messaging: Unlike the launch of the iPhone, when lots of people swore it would never be used for business, iPad comes into the world with native support for Microsoft Exchange. And iPad e-mail is easier to read, write and manage than on the iPhone because of the 9.7-inch screen and bigger keyboard. The native calendar and contact application on iPad are also nice to look at and easy to manage. Unless you live and die with Microsoft Outlook or Lotus Notes and their full desktop productivity functions, there's a good chance you'll really like using what's built into iPad.