I think they're just entertainment for most. Pretty expensive for a temp gauge. I got one mainly for the temp gauge but the tach, temp & speed memory can be helpful. If you're playin with gears, jets, carbs or such and take notes you can track the changes. I figure it's a tool but it depends on how you use it. I like mine for tuning & sometimes it's fun just to see how fast you're goin. I'm upgrading the engine so it should show the improvements. Set up can be easy to difficult depending on how nice you want it. They are easy to program. I don't like that you have to switch screens for temp display but the warning lights will keep you out of trouble.I should say the folks at Trail Tech where very helpful helping me find the right one for my hybrid.
BTW: The mount that comes with it is junk. You'll need to buy or make a good one.