Is A Tankless Hot Water Heater the Best Hot Water Heater?

Mark has a hard time keeping hot water in his house. Every time someone turns on a faucet the person in the shower screams out because the water turned cold. He is not sure how to fix the problem. He decided to get the advice of an expert. He talked to the company that sells water heaters and they advised him that he should get a tankless water heater. They told him that the the water tank did not have to fill up with water and then wait for the water to heat. With the tankless water heater the water would be continuous hot water.