I passed the PSM1 exam with a 100% score. I found the exam a bit different from the practice questions I used while preparing for the exam. I used all the test from thescrumexperts.com site plus Ken Schwaber and Jeff Sutherland youtube videos and got a lot of motivation before I started the practice tests.
thescrumexperts.com initial quizzes set you the foundation of your preparation for the exam. I read a few books, took the practice assessment until I consistently scored a 100% in my exams before I booked the exam.
Do not forget to practice the exams from Mikhail Lapshin as well to boost your confidence if you need more practice.