The rock is smack bang in the middle of Gulang island, so when you get to the top you get great 360 degree views of the island and Xiamen city. The climb to the top is fairly leisurely, avoid weekends, public holidays etc as it will be busy and you will be have to queue on the stairs just to get to the top. At the top space is at a minimum, its only a small viewing platform and you'll be unlikely to have the place to yourself.
Entrance is 60元 and entitles you to visit the large aviary at the bottom of the rock filled with rare birds so keep your ticket after you have descended!
Visit after six o'clock and entry to the mountain is 30元 as the aviary closes at this time and the ticket will only entitle you to climb the rock, worth it though as its nice at sunset. Climbing any later than sunset and you will find that there are bright spotlights pointing at the summit that blind you from seeing much or taking any good pictures.