There's been a ton of new features on maps over the past few years, including indoor maps, indoor streetview, transit info and all kinds of new aerial views. I'm not sure what you'd want from them... after all, they are still a map service.
At least in my experience (in the US) the maps data on Google is much better for cycling routes, partially because users can go in and submit fixes, which I don't believe you can do for the Garmin data.