It's like buying a coach ticket and winding up flying first class. Part of the reason this happens is manufacturers rush products out the door before they're ready. But it's also nice to be able to upgrade. This doesn't always work, of course. In general, most changes lie somewhere between the useful patch I found and the poison pill swallowed by the iPaq owners.
Most upgrades make lots of changes.
Some TiVo owners, for instance, aren't happy about the fact that a recent software upgrade to their digital television recorders changed the way the remote works with a specific feature. Unfortunately, such bulk alterations probably are inevitable. Given the complexities of software, manufacturers would find it difficult to support a universe of devices that didn't largely share all the same computer code. A more pressing concern is the alteration of your devices automatically. Take your television system.