I'm a second year student getting ready to decide how to really dig into COMLEX Step I prep. I received a free set of Youel's Jewels and I have to say it uses a very different approach to organizing info than other prep books I've looked at. I will agree with the above poster: it is a LOT of mnemonics, some of which might work for you and others not so much. On a whim I took the pre-test that's included, which was a bad idea because it sent me into a bit of a panic. However once I started from the beginning of the material, all the answers were right there. I suppose if someone were to use this system alone, he or she could get a false sense of security because the questions are verbatim from what was taught and you don't have to really apply it much so I don't know how useful the test is to gauge your preparedness for the real thing. That said, my test prep is still just beginning so as I get more into it and get a better feel for the YJ system I'll see how it helps me do in other question banks and post again.
