When I visited in 2014 a part was being restored. So what I show is: the Şale Kiosk, some of the park, two pavilions and some of the exhibits at the Yıldız porcelain salesroom. The park offers a good opportunity to be away from the pressures of the big city. It being built on the slope of a hill walking can be strenuous though.

I plunder the Wikipedia for some information:

"Yıldız Palace (Turkish: Yıldız Sarayı, IPA: [jɯɫˈdɯz saɾaˈjɯ]) is a vast complex of former imperial Ottoman pavilions and villas in Istanbul, Turkey, built in the 19th and early 20th centuries. It was used as a residence by the Sultan and his court in the late 19th century.

Yıldız Palace, meaning "Star Palace", was built in 1880 and was used by the Ottoman Sultan Abdülhamid II. The area of the palace was originally made of natural woodlands and became an imperial estate during the reign of Sultan Ahmed I (1603-1617). Various sultans after Ahmed I enjoyed vacationing on these lands and Sultans Abdülmecid I and Abdülaziz built mansions here.
In the late 19th century, Sultan Abdülhamid II left Dolmabahçe because he feared a seaside attack on the palace, which is located at the shore of the Bosporus strait. He expanded the Yıldız Palace and ordered the renowned Italian architect Raimondo D'Aronco to build new buildings to the palace complex. "

When he moved there, the palace became the fourth seat of Ottoman government in Istanbul; the previous ones were the Eski Saray (Old Palace, on the site of the antique Forum Tauri, west of the Grand Bazaar), the Topkapı Palace and the Dolmabahçe Palace.