Eh. A little noisy on the HIGH setting and I didn't notice any difference after using it for a month in my car. The other issue I had was you can't turn off the bright blue light so using it in your bedroom doesn't really work if you enjoy sleeping in the dark. Finally, waving over the top of the device to turn it on and off seems cool until you accidentally turn it off while reaching for something near it. Finally, you can't change the Celsius setting to Fahrenheit if that's your dig.
Would I buy it again? Probably not.