That is pretty cool! I love gadgets like that, but I don't fish enough to get much use out of it. If I stumble into some money, perhaps I will pick one up.
It is a really cool tool. From a fishing perspective you can finally see beneath the surface. Is it worth it to cast over there, what about that spot, etc.? My primary use has been water depth and structure. It is cool to see fish, but when you look out over a body of water you're fishing blind often. Always said you can have the right bait / lure but if no fish where you cast you wouldn't know it.
Another cool feature is the fish alarm. You can put the device where you're fishing, and then just sit back and listen for the audible alarm. Catfishing is great for this. Set your line, set the device, and do whatever. The audible alert can let you know hey pay attention to your line now.
From a non-fishing perspective I like it for water temp, depth and structure. Especially in my pond that I acquired and didn't build. I also like taking it on holiday because it is so small unlike many of the boat mounted options.
