I don't know about Google maps in the US but in Europe it doesn't warn of dangers on the road (cars on the side of the road, blocked roads, etc.). Waze do.
It also has better community mapping as of a few years ago. Everyone in Costa Rica uses it because some of the roads just aren't on GMaps. Also works better with e.g. Road closures due to trees falling in the jungle (and because everyone uses it).
