Our school has access... It's really picky, although I used it to go through some subjects where I wanted more practice, I preferred either USMLeasy or Qbank for most of my studying.
Our school bought access. I used it for a month or two before boards every now and then. It is not nearly as good as qbank, but if it is cheap--probably worth it. It does have good explanation, but unsure correlation with real board exam.