We went during the summer, and children under 18 were free, which was a really nice touch. A taxi from Zhongjie would have taken over 50 minutes, so we weren't in a rush, so we took the subway and a special bus to the zoo. It was a leisurely stroll through the many animals, and crucially, it was very clean. You can bring your own food; the panda park has rice, but the rest of the area only has water and sausage. We took a leisurely trip, visiting only one location in a day, so we weren't rushed, and the experience was great!