I agree in general, but it isn’t all bad. (Recounting my experience on the Retina iPad:) At least on that device, performance now appears to be on par with the old app, much improved from earlier betas (but the new iPad is a pretty beefy device, other devices may struggle more). On bad connections, maps seem to load much better (because they are now vector based) and I do like their style – if it weren’t for the atrocious map data, I think the default view would be on par with the old app (I also have seen the styling of the maps and the placement algorithms for labels improve by leaps and bounds during beta testing). Turn-by-turn is really great and works very well. I have no complaints about the UI on the iPad, it’s more or less the same (though the changes they made might not works so well on smaller screens).
(I’m in Germany, living in a small city with 50,000 inhabitants:) However, map data is atrocious and riddled with embarrassing mistakes (when zooming in, the label of my city is not visible for the longest time – while much smaller villages around my city appear much earlier – and when it finally becomes visible it’s about three kilometers east of my city, in some forest). Satellite images are embarrassingly bad. POIs are practically non-existent and useless in Germany. If they exist at all they are out of date (when I search for italian restaurants, it shows me a pizzeria that closed half a decade ago, not a single italian restaurant that is open now). Google’s POIs are current and (more or less) comprehensive, Apple’s are anything but. Plus: No one uses Yelp in Germany, Qype is pretty popular around here, though – consequently there is just no useful data on Yelp about German restaurants.
I really hope that Google will soon come out with their maps app for iOS. And I hope that Apple will improve. I believe they can (hey, it took Google some time, too), and I don’t object to the existence of a second good maps service.