We have been without an instant hot water dispenser for at least a year. My wife loves it and is so happy to finally get a replacement for the one we had for about 20 years. 
This new one has a temperature adjustment knob on the front of the heater. I think that is an improvement of the prior model we had.
The swapping out the old unit for a new unit went very smooth.
It does make a little noise when it is heating the water, but not very noticeable at all. It is comforting to hear it, so then you notice that it is working.