I guess not. Or everyone knows about them already. Just in case, here is a link. I think these would be a real time saver in setting up camp late in the day if you didn't have enough food on hand. I think there are better videos on youtube though.
I used to use them all the time back when I used to guide. It's best to place the bait just below the surface of the water this time of the year, contrary to what most people think...
No not really problems with the actual device. But Like BB stated theft is a huge problem. It's actual very peaceful to go out, set some yoyos, drink some beer and listen for limbs to start shakin...
They have become very expensive, we have a couple of hundred yo-yos, but it has been years since I went out and ran yo-yo's. It is fun, we catch white perch, catfish and gar on them, but the turtles will eat your catch if you do not get to them first. We bait them with shiners, just under the surface of the water.