I think they're good for practice but are really off when it comes to scoring.
I took the PS and BS of BR1-3 last year and keep in mind I wasn't adequately prepared for the MCAT last year when I took it, but...
BR1: PS: 8, BS: 8
BR2: PS: 8, BS: 9
BR3: PS: 11, BS: 8
Real July MCAT: PS: 8, BS: 9
I know those #s make it seem BR was a good indicator for the real one, but honestly, it wasn't because I completely messed up on the real test day.
On the PS sections of BR, I always finished them on time. I froze up on the test day and had to guess on the entire last passage, resulting in an 8. That last 11 you see on my BR test is NOT because I made dramatic improvement. It was because BR3 for some reason had a ridiculously friendly PS curve while the first 2 did not. So, in other words, I finished all the PS tests under time and essentially got 8s everytime. On the real thing, if I had not folded to pressure, I know I should have gotten ~10 on the PS. Guessing on an entire passage will definitely drop your scores a few points.
For BS, I suppose BR BS was an okay indicator. the BR bio has a lot of WTF passages, so it at least makes good practice. I think BR tests may have way too much ochem on them, though?
I never tested out the BR verbal because I heard it was really off from the real VR feeling.
So, in conclusion, I would say they are good for practice but the scoring is off. You can tell by looking at their top scores. Their 13-15 range on tests is all blurred together. And, yes, I know there is little difference between a 13 and 15 so it's maybe permissible to make a range of scores, but still... They are no more than a year old, so they have not been tested by many MCAT studiers yet. Thus, they obviously can't have too accurate of scales yet. So anyways, it's definitely good practice. Only consider your AAMC practice scores as predictable for your real score.
