Took it last year and i do'nt know if it has changed since then, but it was pretty spot on. the bio/biochem was a bit easier than the AAMC sample test and their own full length exams, but that could have been sicne it was so short. psych and CArs was tough though, bit tougher than the real thing. passages and q got the feel of the aamc, and it was harder than the aamc question pack material.
overall id say it was a very good exam, better than much of the free stuff out there (esp Khan). take it early on, but remember that its such a shrot test, it wont really diagnose your science skills, only your mcat skills like passage reading, thought processes for questions.