I've been following this thread on and off, thought I'd share my test experience.
Just took the beast today! I spent about 3 months to prepare:
1st month: had classes so I only did 1 kaplan qbank a night (most nights...) , took about 3 hours + annotating FA and reading relevant pages in FA. I was getting low 50s/high 40s when I started (which is expected).
2nd month: did pathoma over winter break. DIT when I came back form break (15 day pass). finished kaplan qbank (overall 61%, had a rough start). and took school administered NBME basic science exam - 235
3rd month: Uworld + numerous passes through FA and pathoma for my weak areas. I also went over about 1/2 the questions I got wrong in UW (ran out of time). 2 weeks before my exam I took NBME 7 - 248. finsihed UW with 74% (was getting upper 70s/low 80s consistently in the last 15ish blocks). my last 10 blocks averaged to 78%. The week before my exam I hammered home the short term memory info, i.e. embryology, biochem, pharm, and micro.
Exam day:
I can't say specifics about the exam, but I can say it was more challenging than typical UW questions and several levels above NBME. I feel like NBME questions are just too easy to actually prepare for the real thing. It might be a good score predictor, but I got a lot more out of doing UW questions and reasoning my way through things. I spoke with several third and fourth year students and they all claimed that their real exam was similar to UW (difficulty wise), but I feel like the Step 1 is going towards a new direction, i.e. no more buzz words, no more classical phrases, longer more complicated histories with multiple issues and plenty of distractors. All in all I don't think I could have prepared myself any better for the real exam. The test just comes down to applying your knowledge, performing on the day of the exam, and hoping for questions that test your strengths.