I would say the side imaging from Humminbird is the most productive electronics I have purchased. Dollar for dollar, I think it has put more crappie in my boat than any other I have owned. That said. I still carry a hand held GPS not because I can not get on a waypoint with the Humminbird but because I can do it so much quicker with my handheld. As for marking cover and going back to it, I have no problem doing just that but I still move that point to my handheld for future visits. Side imaging takes time to gain understanding of all the things you see. First you will identify the obvious. Over time you learn to recognize the little things. I compare it to reading X-rays. Ever been to the Dr office and they hang a X ray up there and you see nothing till the Dr. points it out. Then it is clear as day to you? That is side imaging.
The transducer MUST be installed correctly. This is not a hurry up job.
There is high sensitivity to interference but this can be addressed.
Without a moments thought I would buy it again.