It's good as a subject-wise question resource, much like Kaplan Qbook, and both have good questions and good explanations. If you are going to buy two qbanks, then buy Kaplan and Uworld. If you are only going to buy one, though, you could do First Aid Q&A and Kaplan Qbook to affirm your concepts, then buy USMLE World for your one good random question bank. I liked the explanations in FA Q&A. Hope that helps!