Neuroscience PreTest Self-Assessment and Review, Sixth Edition (PreTest Basic Science)
While the text does a great job emphasizing the different aspect of CNS neuroscience, it is week on the PNS which is extensively tested on the shelf exam.
Also, there is no psychopathology or neuropathology, two topics which are also tested on the NBME shelf.
Therefore, you will need additional study material for those topics. Otherwise, a great text. It might prove more useful for the step 1.