Few weeks back I appeared OCE-WS exam 1z0-897 exam and I cleared it .
I dont want to discourage people but this exam needs serious preparation. I didnt get enough time to prepare (less than 1 months) but you should spare at least 2 months for preparation ( also depends on your experience on WS).
I would like to take this opportunity to thank to Mikalai Zaikin for his notes and help during preparation. His notes and quiz are really good material to prepare. Best thing about quiz is it also explains very well why your answer is wrong which clear lot of ambiguity in your understanding.
I would also recommend to read Ivan A Krizsan study notes which has beautifully covered some important topics.