There are a few episodes dealing with demons and other "supernatural" forces that may be scary for younger children.
Though there's some violence committed by protagonist Kwai-Chang he still may be considered a splendid role model with his calmness, self-control, justness, 'no-nonsense' attitude, selflessness, staggering honestness, insight and wisdom. The show also has some educational value now and then regarding difficult and sometimes controversial human issues. The show deals with such issues (like honour, loyalty, dependence, responsibility, anger management, greed, confidence, vengeance, love, trust, pursuit of happiness, etc.) in a manner that makes it easy to process for older kids, without openly (or manipulatively) pushing through some Buddhist (or other specific) belief system.