I have a Matrix 17 and have used it for almost 2 years it is used with the transducer on the trolling motor, right beside it I have a Lowrance X-60 the transducer for it is in the hull just a little bit behind the front pedestal the reason I mentioned this is because it gives me a good comparison on the accuracy of the two, both almost always shows structure the same. What I like about the unit it is very user freindly,accurate, good screen clarity. My 17 is used with a Garmin 76 with the cable to connect the two you can use your handheld to act as gps antenna the 17 will display coordinates,mark waypoints ,tracks,routes etc. but these features are very generic compared to my handheld. Also when the two are connected I use the 17 as my speedometer change the view until you get the large number display and it is easily read from the console. The best feature the same cable that connects them also powers your handheld from your boat battery and displays the voltage left.
What I dislike is the way it doesnt show tenths of feet unlike the Lowrance, and what I mentioned above about the gps features are generic.
I think it is a good unit for the money but if I was going to depend on it for my primary unit I would save some more money and buy a Lowrance. If you have any specific questions I will do my best to answer them hope this helps in your decision.