We didn't have AMAZING results like some people (i.e. "It worked in two hours!" or "Our dog never barks now!"), but there has been definitive improvement, which for us, is still wonderful!
Our dog is a rescued one-year-old Beagle/Jack Russell mix (yikes!), so his energy level and need for "fun" are insatiable. A lot of his barking was due to boredom, but we have lives to live that can't include him every minute of the day.
At first, the BarkMute collar vibration was causing him to bark MORE, but...