I've been running the betas on my iPad for awhile now and it is really pretty great having the multitasking support. Like the iPhone, it's mostly not "real" multitasking, so when it comes to interruptions and the like you shouldn't have to worry about that. The iPad also has considerably more RAM than the iPhone 3G had, so it can keep a lot of apps in memory at once and the switching becomes reasonably seamless and quick. During the betas, 4.2 was often very slow, but as soon as it went GM performance jumped significantly. As far as I can tell, it's just as fast as 3.2 was - only with all the added benefits of the new features.