It works but you must be patient. I've been wearing it for about 5 years and my improvement has reached 90%; I have astig plus low-grade near-sightedness.
Do not wear it more than 10 minutes each time. Multiple times a day is ok but I wear only once a day and still got improvement. The other action required is try not to wear your glasses once you are using the pinhole glasses. It might make your eye muscles tired and you may have to close/rest them for 10-15 minutes 1x to 2x a day.
If you can't follow the above it may lengthen your improvement or you might not find any at all. But don't expect quick fixes since our eyes took so many years to deteriorate and probably takes half the time to improve back.