Entry ticket is cheaper during winter and you must get a local guide (they are all waiting at the gate). Otherwise, the palace is really dull. Talk to them, and engage one that you like. It cost us 100+ rmb and they will take you from the main gate (wu men), main chambers and the last gate. It's really interesting as they tell you about some history, myths and offers you their views.  Be free to argue and ask lots of questions =)