Since years and with different phones: Navigating when driving in a car works perfect.
Walking around as a pedestrian fails so many times (map does not move, turn, etc.) without any message (bad reception, GPS-Signal, ...).
I've found it to be okay, but it does tend to tell me to turn down a road after I've just walked past it!
Also, it says things like "turn West", like I have a flipping compass on me to check which way west is. Why can't it say turn right or left since it knows which way I'm walking?
I use map differently while walking. I first check where is my target location as per my location with compass (map shows compass and helps if I know where east is from where I am standing).
Then walk few distance and check map again and compare my location with target. This is much faster way, I found.
When walking I don't rely on the voice, but on common sense, I zoom out until I see the marker on the destination, then I just walk according to the path line. From the movement of my location marker I know if I am walking in the right direction or the opposite and adjust my direction accordingly if necessary.