You purchased a tankless water heater for its efficiency. It helps lower your heating bills because it only heats the water at the time it is needed. On-demand hot water means no one has to experience the outrage of a cold shower because three other family members showered before you.
On-demand heating means a tankless water heater does not work as hard as a large tank heater. They have a longer lifespan. They are a lower maintenance option. This does not mean tankless water heaters are maintenance-free.