In a way it would probably be good for me to have as an encouragement to drive smoothly. I did investigate one when I first got my car but it actually turned out more expensive
I think I'd struggle with one round here though, the roads are narrow and windy and whilst you can drive along them safely at speed it would send the accelerometers all over the place. You do get some idiots that do insist on driving in the middle of the road too, and that's an issue when the road is only just wide enough to pass. Come summer it's awful with the tourists, there's nothing more frustrating than getting stuck behind one driving slowly... when you're in a tractor! Seriously, it shouldn't be possible to catch up with someone in a car whilst driving a tractor.