I used CMMRS for class and now I am using it again for the Step. It was amazing for the class - explanations in the text are very simple and tables are great to cram lots of info relatively quickly. Mnemonics may seem silly but you will actually remember a lot of them.
Now that I am preparing for Step 1, I just annotated some stuff from CMMRS into FA (usually clinical presentations of different conditions); quickly glanced through annotated FA (no proper studying) and I am getting ~80% on UsmleRx micro section.
You might need to supplement some of the topics if your class exams focus on a lot of details (I supplemented some chapters, especially general micro with Levinson's)
Overall, I think it's a really great book (once you get past the "annoyed" stage).