When it visited Shuri Castle, in the May last year it was already quite warm and since a lot of the viewing was outside, it was quite hot. Inside there is a rout that you walk and are able to see the inside of the castle. The building itself and the inside were pretty, but apart from viewing the castle there was not much else to do. You can walk the route and see the castle in under an hour.
World Heritage Shuri Castle tells the ancient history served as proud and dignified center of Ryukyu Kingdom. Architectural itself influences from both China and Japan. It is great to visit here to learn the culture side of Okinawa. Just remember to wear a pair of good shoe to walk up there.