Product review (5 stars): Paid for itself in under a year.
I installed this unit just over a year ago.  It took me about an hour to get it installed and the sensitivity setting of the on switch properly set.
I've not had to mess with it since then.  Of course, I also spent some time cleaning the long vent pipes prior to the installation (about a 60 foot equivalent run), which needs to be done occasionally so I don't count that in install time.
The unit has run fine and drying times are shorter, although I don't have an exact pre/post measurement.  My electric bill was $17/month lower on average over the year, compared with the prior year. This is with electric rates at about $0.10/kwh, in Kentucky. Rates were up a fraction of a cent over the course of the year.  I did not make any other significant changes in my electric usage in that time, and average temperatures were pretty similar so I do not think HVAC usage accounts for the difference.
So with our fairly low electric prices here it appears to have paid for itself in under a year in addition to speeding the laundry cycle and hopefully extending the life of my dryer.  I'm very happy I got it.