The Apple iPad ushers in the era of tablet computing, with a slate-style handheld that looks nothing like a typical computer. in fact, the iPad is more reminiscent of an oversize iPhone than a laptop. But because the iPad's screen is three times larger than that of the iPhone/iPod Touch, you'll be tempted to use the iPad for activities you wouldn't consider doing with an iPhone. Innovative apps and content optimized for the spacious, high-resolution touchscreen make the iPad a treat to use. Nevertheless, the iPad's other limitations make it hard to recommend as a replacement for (rather than as...