Totally deserved those 9 Oscars and a must watch. Don´t worry about the length, is a so well paced movie and the argument is quickly developed.
The Last Emperor follows the life of Puyi through a long part of China´s 20th century, so it´s an amazing journey across the great changes of that period of time, we can see that in social general portray, but most important, we can see all those changes in a single person. Puyi is an amazing character because at the very beginning when he is locked in the Forbidden City is really pitiful because of his lack of freedom and because he represents the fall of a great period, the fall of a long time of dynastic power. But as he grows up he changes into this person you just can judge as a normal person with imperfections.
Music is also great as it marks differences between the traditional China inside the Forbidden City, and a country outside that place which had to endure a lot of drastic and sudden changes, so we listen to both: traditional Chinese music and western music.