I did a 4500 mile solo trip out west in 2011 and a 2500 mile trip with friends to Deals Gap and Barber with a DroidX as my GPS. In 2012, I bought a Zumo 220 ($400) motorcycle specific GPS. It doesn't do music or cell phone, it does link to my Sena but I don't link it, I just look at it. I then did a 6500 mile solo trip from Peoria to Glacier to Seattle, then down 101 to LA to home. In my opinion, having done both, the Zumo was the best money I have ever spent. Way better on the bike, way better off the bike, I use Garmin sw to make the routes, download them to the GPS and bang, when I get up in the morning, I just pick the route for that day and follow it. Yes, I planned every day of all the trips. I changed them some on the fly but that's another post topic entirely so let's avoid that.
Zumo does gloves, vibration and rain and is MADE specifically for navigation. Once one I was coming up to a turn using the DroidX, a text popped up and blocked my directions. I was riding down the interstate in the rain and in seconds, I had to stand up, sit on my glove, pull out a bare hand, make the text go away and put my glove back on. Yes, I realize a configuration option on my phone would have solved that problem. Didn't really matter at that moment in time. I know what I like and I have done about 6 trips since, some solo and some leading groups as large as 8 (which sucks in another whole way but ...). I know which I like and that's what I do. If you want to do something else, hey, knock yourself out. I would just prefer not to hear I am doing it wrong.