Summary: I recently purchased this unit in July of 2013. where as the GPS portion of the unit is good, the sonar has a big problem . Going slow, everytime a move from shallow water to deep water, the sonar loses the bottom reading and locks up. Sometimes it will reacquire the bottom on it's own after a minute or two, and sometimes you have to reboot the unit completely for it to reset. Worthless for fishing and trying to follow a contour line.
Summary: I bought this for our vacation on Lake Erie. As a new boater to the great lakes I wanted an insurance policy. After we came out of the marina after dark I realized why they call it a great lake. I have never experienced that kind of vastness. I navigated back to the hotel ( an hour and a half trip) completely by GPS. Our last day was very stormy. I just plotted a course to the marina we were heading to and away we went. No worries, just plot and go.