Well, pretty much every 10.x.0 OSX release has had some nasty regressions in it, but they're generally not quite as easy to spot as the maps fiasco. What's worse is that this isn't a new product that starts off a bit crap with the view of improving it over time - there have been a few examples of these as well.

Instead, from the users' point of view, the maps update falls plainly into the "if it ain't broke, don't fix it" category. Users don't give a damn about contracts between Apple and Google. The Maps app has been there since iPhoneOS 1.0 and it's not had any drastic changes since then, despite its tremendous popularity. I find it baffling that they didn't release the new map material as an extra mode with more features (3D, turn by turn navigation), in addition to Google's map material for the classic 2D view until iOS7 comes along. That would probably have completely avoided the problem and given Apple an extra year to get their data into shape. The new features, although a little half-baked, would still have been seen as an improvement by users, whereas now they're just blinded by the seething rage of having the core functionality yanked out underneath them.