We live in rural Devon and we'd been plagued by wood mice for 15 years - in all parts of our house, doing £100s of damage. Since we installed this device over a year ago, they've left us alone. Still rife in the garden & outbuildings, and in neighbours' houses, but our house is currently wood mouse free...
So I'd say, give it a try. Maybe its effectiveness varies from species to species. Could be the people it's not working for are dealing with house mice (grey/black urban animals) rather than wood mice (brown rural counterparts).