The main limitation of all body composition assessment methods is that they are based on assumptions (eg, a certain percentage of body fluid). The only truly accurate way to assess body composition is through cadaver analysis.
No method is more than 1% accurate, which means that at best we can estimate body fat to within 700 grams in a 70 kg person. However, skinfolds are best used as a monitoring tool over time, with the same person taking measurements each time. This simple, fast and cheap method allows measurements to be taken anywhere.