I have used few times Google maps. Not for touring though. The big advantage of Google maps to me is I can plan exact route on Google maps on my PC in advance.
I also use google map, tweak the route on my PC, then send it to my phone. Used it today for a 150 mile ride, only problem my phone runs down really quick while using maps. Went flat within 5 and a half hours, usually lasts up to 2 days. Really need a power source plugged into the bike if your going any distance