http://www.ripoffreport.com/searchresults.asp?q1=ALL&q4=&q6=&q3=&q2=&q7=&searchtype=0&submit2=Search%21&q5=riddex&Search=Search
Of course its supposed to take several weeks.
Ive heard 1-2 months overall for some.
Despite reports of it being a scam, its been working for us.
A device that covers an effective area of 350 sq. ft. would ideally cover a circle of less than 10 ft. radius with the device in the center of the circle. So the device has an effective range of 5 feet. Sound pressure varies inversely with the square of the distance, so if you put the unit in the corner of a 10 ft. square room you would only get one fourth the sound pressure over the rest of the room, and only one eighth the sound pressure at 20 feet. Furthermore when cone speakers are used the sound is 'beamed' directly in front of the unit, likely covering a 5 ft. x 5 ft. x 5 ft. triangle directly in front of the unit (with the apex at the speaker cone). Knowing this you might be able to drive mice and insects away from that 'sweet spot'.
Sound frequencies are absorbed by soft surfaces and reflected by hard surfaces (like your concrete basement), so sonic pest repellers placed every five feet in your basement or crawl space might be annoying enough to drive mice or insects away. After a few weeks they might all leave the basement and build their nests in your house.