I just finished mine a few hours ago and I feel like I've been forceably kicked in the nuts. The first block was OK, and then it got harder and harder. My last block crushed my spirit. Mine was very heavy on molecular and (my worst subject - hands down) pharmacology (I'm particularly bad with antibiotics). My strong subjects were hardly touched upon at all. I would have entire blocks of 8-10 questions in a row where I'd either have no idea or only be able to eliminate an answer or two.
Moreover (though time was never an issue for me), the question length seemed almost DOUBLE the standard question length on NBME's. I'll be lucky (very lucky) to equal my worst NBME score (which was nothing to write home about as it was).
I've never felt this bad after a standardized test before.
judd