Is organ meat such as kidney and liver good for you?

That depends. Beef liver and kidney is notoriously high in cholesterol and contain a significant amount of saturated fat and even a bit of trans-fat. These meats are high in protein, iron and vitamin A content, but could be too rich in fat for the today's typical sedentary lifestyle. If, on the other hand, you live a lifestyle closer to that of our ancestors, with high level of physical exertion and not a lot of processed foods, then organ meats could be very healthy. Indeed, for our remote ancestors they were essential.