Xiaojian D.
Yelp
This is definitely one of my favorite Swiss castles and even though my Swiss Travel Pass got me in for free, I'd highly recommend paying an extra 6 francs for the audio tour, which is available in a plethora of languages (English, French, German, Chinese, etc.) You can easily spend 2+ hours here to admire all of the exhibits and learn the medieval history surrounding the castle. It's also not a bad idea to come here when it's really hot like during this unusual May heat wave when I visited - the underground dungeon where Lord Bonivard was held is a wonderful relief from the heat without the need for AC. You also get to see real examples of swords, armor, banquet halls, treasure chests, and all sorts of artifacts of medieval life that you normally only see on TV or in role playing games.
Oh, and you also get amazing views of Lake Geneva from the many windows where guards and scouts stood hundreds of years ago to protect the Savoie from invaders and other unsavory (no pun intended) characters.