Yeah, I ended up purchasing USMLE Consult for 3 months. So far, I find it is a great study tool. If I get a question wrong (or right), it has explanations for each answer selection, as well as "High Yield" information on the topic. What I like about the High Yield Information, it comes directly from textbooks (it sites it's references). In addition to that, when you review your test, it indicates the topic of the question (e.g. Normal Pressure Hydrocephalus). It links you to MdConsult, so you can look up the topic (although your access is limited to the topic). To gain access to the whole topic and/or different books, journals or articles, you will need a subscription to MdConsult.
So all in all, I find that it is a good study tool. My subscription ends in June. For the last month before I take boards in July, I'll be using USMLE World. All the best!