Hope I'm not violating any forum rules by posting a link to a thread elsewhere. I have a Triumph Tiger and also spend some time on ADVRider. There is a pretty good thread that discusses the question of "designated GPS vs smartphone"
http://advrider.com/index.php?threads/designated-gps-unit-vs-smart-phone.936814/The GPS 101 also has a ton of reviews, etc.
http://advrider.com/index.php?forums/gps-101-which-gps-for-me.75/I currently use my phone so I can hear music and the map through the IS's stereo. I like the way I have it mounted and have a charger set up for it, but I always worry about it in the rain. Also, the point they make about the micro USB point wearing more quickly than dedicated GPS units seems accurate. Seems like my phone's port has taken some wear.