I passed this one yesterday. Very glad it's over. Two years ago I got 1.4 certified but wanted to update my skill set and make sure I knew 1.5 language features well. Studying for the exam certainly did this.
My study approach:
1. Leisurely read K&B book over course of about a month. 2. Did practise exam at end of chapters. Did poorly (~50%) 3. Revised book making flip cards on interesting points for all 10 chapters. By the end I had 10 envelopes with cards that summarized the book 4. Got friends to test me on the cards and read them on the way to work over the course of 2 weeks. 5. Did practise exams (CD from book, Inquisition webstart program) over 3 days. Questions I got wrong I confirmed in an IDE to see why. (Note sometimes the answers provided in mock exams are wrong and you were right in the first place ... always check in an IDE!) 6. Took the exam and got a good score.