Honestly, it's one of those small gadgets you hope you'll never need, but just having it with you gives you an extra sense of security. I always have it on me, attached to my pants with a carabiner so it's always immediately accessible, and because it's very compact and lightweight, it doesn't bother me at all in daily life. Although it's small, it looks quite serious as a tool and the build quality left me with a much better impression than I expected.
I have tested it on an abandoned car, both for cutting a seatbelt and breaking a side window, and honestly, it did exactly what it promises without much difficulty. The mechanism for the glass works much more powerfully than it appears from the outside, and the cutter cuts the seatbelt very quickly when it finds the right angle. This personally gave me enough confidence to always have it with me on trips or when spending many hours on the road.
It's also good to have it in an easily accessible spot and not lost inside a bag or glove compartment. For me, it's definitely one of those small things that are worth always having on you or in the car without a second thought.