Product review (5 stars): Great Product.
Here's what it did for me.
I really dislike washing my hands in cold water... so that issue is gone with a push of the button and 45 seconds.
I don't know exactly what the savings will be in the long term... i suspect it will pay for itself in a couple of years.
I do know that here in San Diego sewer charges are  added to the water bill. Sewer charges are roughly 2x the water cost.
Time to get hot water at tap.
  *  Pre-Device - 35-45 seconds
  *  Post Device installation- 1-2 seconds.
Therefore this device saves me 3x what 40 seconds of water costs... 3 to 4 times a day.
Basic logic and math... says it adds up.
I like saving as much water indoors as it offsets the little extra I use watering my tomatoes and peppers.
We all have priorities. Water in San Diego ... is one priority we all share.