I used this to study for the Oracle PL/SQL OCP exam (1Z0-146). Having just passed it, I feel I must recommend it for this purpose. It covers all the exam topics, and goes into further detail on several topics, which I found to be useful for filling out the gaps. It also covers topics from the previous exam (1Z0-144) which I mostly skipped over, having completed that exam earlier. It lacks any control questions after each chapter, which might have been useful.
While somewhat dry in places (unavoidable given the subject material) I found it to be thorough. A good supplement to Oracle's student guide.