Greetings,
I don't know about the UK, and other places in Europe, but out here in California the new map program works vey well. I checked several other states, and countries in South East Asia, that I know fairly well, an they are accurate. The turn by turn works pretty well, too, here at home.
So the program seems to work well in most places. If it didn't, a lot of people would be screaming, instead of only a couple of hundred. Most of those posts are posts from the same complainers, as well.
I've also talked with several colleagues of mine around the globe and they are happy as well. It may be that some parts of he database is not up to snuff yet. Since it's a dynamic database, the accuracy, speed, etc, will only get better.
If there is a serious issue, Apple will address it as soon as they can - a little patience is needed with some folks. Anyway, I'm happy, even though I rarely ever use the Maps app - I have a near of the line Garmin, and a display built in one of the cars.
From what little I have used he Map app, Googles or otherwise, this new one is just as nice. Besides, only a fool would rely on one of these things for turn by turn, for complete accuracy. None of hem is a hundred percent accurate, and a little common sense is needed sometimes.
Cheers,
M.