I tried a couple of decent phones before I got the Garmin and you're right that they track the route perfectly well. Where I've noticed a real difference is when using the device to navigate, rather than just track the route. On both phones, the 'distance to next turn' was rather unreliable, and I overshot a turn on my last ride using a phone, as it said I had 100yds to go at the point I passed the turning (a fairly well hidden path, so easily missed). The Garmin has been pretty much spot on since I've been using it, and I'm allowing myself to rely on it rather than double checking the map constantly, as I did with the phones.I don't think this is true anymore - I've used GPS on my Huawei £80 phone and on a GPS bike computer, and they're both pretty much equal, even when I've tracked the same ride with both devices at the same time the accuracy is pretty much the same. In fact the phone has the benefit of locking onto a signal almost immediately because it can use mobile phone masts and local wifi networks to locate itself, whereas I've sometimes had to wait for a minute or to for the GPS device to lock on at the start of a ride.