Very unreliable, it's great when it works, but all too often it gltiches, freezes, making you miss your turns because it doesn't tell you and cost me at least half an hour extra driving the other day. Began glitching out again today, it doesn't always tell you if GPS signal is lost, and when it does, it doesn't tell you if it had re-established a GPS signal. Services like this are no good if it can't be relied upon.