Pros: Very economical, endless supply of hot water
I am very pleased with this water heater. Waiting 30 seconds for water to warm is not a problem when you consider the waste of a conventional water heater reheating water constantly. My old house was three stories with a conventional water heater in the basement and it took at least the same amount of time for the hot water to reach the third floor.
I now live in a one bedroom apartment loft and have the water heater installed in the bathroom above the toilet to avoid the cold in the garage below. I believe local building codes for new construction should mandate the installation of tankless water heaters.