as a whole, the "released" questions are a cake walk compared to the actual usmle format questions. i got high 80's on it, and took step 1 today, and probably 20 or so questions were like them, but the rest were a far cry from them. if you ask me, it is a good way to review some basic concepts, but you have to build on them in order to have the depth of knowledge you need for step 1. hope this helps.
cheers.
andrea