All the data still appears to be there, you can still zoom in to what I assume is the same level of detail you have always been able to see but there are no streets/landmarks/cities on the map anymore.
What would the reason be for doing this? I know North Korea are secretive and would understand them demanding that certain areas, or the whole country, be blurred out but simply removing the city names doesn’t seem to achieve anything. We still know where they are.