I cycle in a mid-cized American city that has had a "Bicycle Friendly America" Silver ranking for several years now, and the Google Maps bicycle directions have been extremely iffy since they were introduced. I just checked how Google Maps routes my normal cycle route home, and it's very close to good, but in fact is quite bad.

It routes me onto a dangerous arterial road rather than the pleasant multiuse park path that is directly adjacent to the arterial road (and which is my normal cycling route). The Google Maps recommendation here is quite bad and possibly dangerous. The alternate route goes on another heavily-trafficked road rather than the quiet surburban street a block away that is a designated cycle route marked with bicycle signs and sharrows (which was my previous cycling route).