Having just acquired a new Garmin Nüvi 3790T sat nav which shuttles between two vehicles, I decided it would make sense to protect the unit from accidental scratches by applying a film over the screen. I already use such products on camera back screens so was familiar with the way they work and the need to keep everything dust free.
I applied the Vikuiti film in accordance with the instructions, making sure to do the job in as clean an environment as is possible outside a laboratory. Despite this, I found that several tiny pieces of dust managed to get between the film and the screen, leaving annoying little 'blisters, where the film would not lay flat. These did not go away as the film settled over 48 hours and eventually, I decided to start again with another film. Sadly, I have to report that I still experienced the same problem although I just have the one stubborn spot remaining, near the microphone slit.
The film itself seems excellent although time alone will tell if it repels scratches satisfactorily. My only caveat is that it is VERY sensitive to any impurities coming between the film and the screen surface and, if your experience is anything like mine, you will need a great deal of patience and ultra clean atmosphere in your room to position the film accurately and without blemishes. For that reason, I can only rate it four stars.
Incidentally, I noted the comments from other users that it is difficult to ensure the microphone slit is correctly aligned when starting the application process from the opposite end. I started with the microphone end, carefully peeling away the backing paper using a craft knife blade to get it started. Thereafter, follow the instructions as printed.