Looks like it's all covered, just not in "detail". That could mean that it doesn't include "POIs" or something.
Just not in detail... It could mean it has just the main streets but not the smaller side streets (like "Close", "Crescent", "Mews", "Alley"). It could be missing house numbers. You'll know when you plot a route and after the usual speech it says something to the lines of: "On your way to your destination, turn-by-turn guidance may not be available". Although I have heard that message and it turns out, it was because it was navigating a parking lot lol.
