Love and hate my GPS

I have this Garmin GPS navigation system in my car. Loved it when I first got it. Took me exactly where I wanted to. Can really be dumb while driving and just follow the voice. But on our last trip to NJ, it took us at roads we have never been to. It took us 5 and 1/2 hours to reach, when according to Mapquest, its just a 3 and 1/2 hour drive. I was so mad. It was so frustrating. Lesson learnt: Never trust the GPS when you are going long.