I had an accord (with navigation) before I purchased the 2013 335i (f30). I always felt that the navigation lacked something in terms of displaying street names on the maps. I got a E90 loaner from my BMW dealer yesterday which also happened to have navigation and I instantly found it much better.
So here are the problems with the navigation system:
1) Hardly any street names appear at ALL zoom levels. I've noticed 800ft displays the most number of street names, but still not enough.
2) Irrelevant street names are displayed. The names of major streets are not displayed while some random internal micro-street names are displayed. WTF? It is not that the map does not have the data about the major street names -- it just does not display them most of the times.
3) The street names take quite a while to start appearing. If you are in a moving car you would have most likely moved out of that area before the navigation decides to display the street names in that area.
Here are two before and after images of the same map region as displayed by the navigation initially and after 120 seconds. (ignore the actual times, I had to restart the car a few times to get the shots right)
BEFORE
AFTER
Also a video that shows this phenomenon: