I bought this to look for cold areas of my walls and ceilings to help plan additional insulation, and for that it has been excellent.
In my house it quickly located uninsulated single skin areas of wall behind the deep eaves of my old bungalow. In my son's, it showed that recent cavity wall insulation had missed the areas above the windows.
Just one real fault, and one annoyance (other that its temperature reading being consistently a bit out), namely . . .
1. The laser on mine is very badly misaligned - it points down and to the left, way outside the pretty large area being measured!
2. The light will only come on after the trigger is released, ie. to illuminate a held reading. If you are working in gloomy areas, you will need a torch to help you see the readout if you want to watch how the reading varies as you move from place to place.
A flawed device, but excellent for this particular task.