My Garmin 520 has worked great for me. No issues whatsoever. I use the Bluetooth tracking with my phone when I go for a long ride so my wife can tell if I am any trouble. I don't use navigation much so I can't comment much on it, but everything else works great.

Got a chance to test the Incident Detection feature last Friday when I got hit by a car. The crash detection system detected the accident and my wife got both an email and a text notification of the incident, including the location of where it occurred. She was on here way before I had my wits about me. When I had got my wits about me, I looked at my phone, which was asking if I was OK. I chose yes, but my wife didn't believe me (rightly so). But it worked. In a more severe accident I expect if the phone gets trashed, it won't be of much use. (I fared OK but my frame is trashed).