Rowing machines are often used by people who are looking to get a full-body workout, and also by rowers to stay in rowing shape during the off-season. According to Men’s Total Health, rowing is a natural motion, and is therefore fairly easy for anyone to pick up and do properly. Also, rowing is a low-impact exercise, meaning that the potential for injuries to your joints is lower than on such machines as treadmills, for example.
As far as “racing”, I said an air rowing machine is better because the Concept2 is the only model used for indoor rowing competitions, setting world records, and entering your actual scores online. It is because their monitor can calculate the drag factor of the flywheel in real time and accurately calculate distance and time. Small changes such as dust build up, air temperature, and humidity will not change the times between different machines because the drag factor is calculated every stroke.
From a fitness perspective, the WaterRower Natural works 84 percent of your muscle mass, helping tone and strengthen your muscles while burning far more calories than most other aerobic machines. The exercise is also low impact, as it removes all the body weight from the ankles, knees, and hips, but still moves the limbs and joints through a full range of motion--from completely extended to completely contracted.