well since I obsessively checked this forum to see what other people had to say, I feel like I should contribute my experience. I took it today, and while it's sort of a blur, I'll post what I can remember.
my test seemed pretty fairly divided between subjects. The difficulty of the blocks did not seem even, with the first two and last one seeming harder. (although with the first two, I might not have been warmed up yet)
I had about 5 embryo questions and they were all very easy between first aid and qbank.
The anatomy was a mixed bag. Half of it was stuff that was emphasized in Q bank, half of it was stuff you maybe could have figured out from the image or remembering basics. I think first aid was pretty worthless for anatomy but I wouldn't have used anything more, except maybe spent a little more time (like 20 minutes) going over cross sectional anatomy of the trunk. Probably about 10-15 questions total.
Neuro on my test was really easy. And I am not that good at neuro if it gets tricky. pretty evenly divided between central and peripheral, maybe 3 questions per block. There were an annoying number of questions about cell physiology of neurons which I did not review at all because it's not in first aid or qbank and I had to try to remember from first year. there is a chapter on cell phys in BRS path I could have read and probably would have in retrospect.
I thought the pharm on my test was pretty hard. I was doing pretty well on pharm on Q bank and USMLERx by the end, too, for what it's worth... I might think it's hard because I can only remember a few questions that I really had absolutely NO idea on. I think there might have been a bunch of questions that were really easy too that I've forgotten about. also I got a LOT (probably 5) questions with graphs of different inhibitors and various questions about that, easy if you've practiced it. my test was maybe 10% pharm.
micro was mostly straightforward, no worms, a couple of parasites, very few viruses, a few fungi. mixture of mechanism of some aspect of infection, name the infection, how do you treat it... no idea how many questions, not a ton. Mostly really straightforward and from first aid, a couple I had no idea on (but still could be in first aid).
path/pathophys/phys was the bulk of the test. I think it was more renal and cardio, but pretty even among most stuff. there was maybe one derm question, I think I got every single question about bones wrong. Reproductive was harder than any of the NMBEs too. Overall, there were a couple of case presentations where I had absolutely no idea what was going on, one where I had heard of the random disease mentioned once as an afterthought in class, but not the details of it... hopefully experimental. I thought that path in general was harder than the NBME exams, where I didn't really have a problem with it.
I thought I had sort of a lot of histo/cell bio (not a ton, definitely less than 10 total) and not so much images but descriptions and I did NOT do well on those questions. sometimes I'd figure out the answer like on a break after the next block. stupid. Q bank does not have enough of those questions and first aid only has like a page. that is one thing I would have liked to have spent like 2 more hours reviewing and it would have been really easy points, they were not hard questions. maybe high yield histo would have been a good investment.
Biochem was mostly okay. I spent a LOT of time reviewing it, because I felt the weakest in it. There were a couple of questions about tRNA-type stuff that I had no idea on, but other than that, not too bad. The metabolism questions (which I was terrified of) were really straightforward. like people have been saying, KNOW the signaling of the alpha and beta receptors. Knowing signaling pathways in general was probably good for 5-10 easy questions. (insulin, growth factors...) If you feel weak at all, HY cell and molecular has it all. I thought the immunology on my test was REALLY hard. and I work in an immunology lab. there is NO WAY you would have gotten some of the questions just knowing first aid (like you needed to know multiple names for costimulatory molecules in MHCI vs II presentation of antigen). but maybe the really hard ones were experimental. and there wasn't that much.
Behavioral science questions were way better written than q bank. I had at least 10 what would you says, but 7 were no brainers at least. I got a LOT of questions about epi also (2-3 per block), I'm really glad I reviewed it the day before, and glad that my school DRILLS us with it till we want to die of boredom.
I think there were at least two questions with no answer. one was a biochemical disease where they named an enzyme that causes a disease and asked which disease it causes and then listed 5 diseases, none of which were the one it caused, and the other was a genetics question, where I checked my work like 5 times (although I could still be wrong about that one, I guess.) I guess that's what "experimental" questions are? I think they're just trying to mess with your (my) head, but I can't figure out why. Fortunately, after the disaster that is multiple choice exams at my school, questions with no correct answer don't faze me too much, hahaha.
I thought that the NBMEs were the best source of practice questions, once I had finished reviewing all the material once. they were pretty dead on about some of my weaknesses (information which I used better in some areas than others...) also, I definitely feel less good about this than I did the NBMEs, I'm hoping it's a combination of (a) experimental questions are hard, and (b) on the NMBEs I would go back and check (but not change) my answers so I knew if I had guessed right, whereas now I don't. I'm pretty sure I passed, at least, but I sure don't feel terrific.
also, I had time issues on some blocks of the actual test, which I did not have on the NBMEs, mostly because of a few WTF questions (probably experimental, but you never know) or just forgetting facts that I thought might come to me (sometimes they did). and I am normally a really fast test taker, at school I am one of the first ones done with our tests, I finished some sections on the MCAT like 30 mins early... I got through everything once no problem, but on a few blocks I could really have used a few more minutes to think.
I hope this helps someone, or at least makes you feel better about the test. good luck to everyone who still has to take it.