I prepared for about 2.5 months, although had a new baby at the time so couldn't study as much as I wanted. Studied by going over NBDE part 1 & 2 dental decks. I thought the Clinical Sciences section was really straight forward and pretty easy, but I attribute that to being out of school and practicing for several years. Just my thoughts.
The percentages changed as more people took the exam. I put the ADAT score in parentheses, however these numbers don't really mean much at this point since the exam is so new.
ADAT overall: 94 (610)
Critical Thinking: 94 (630)
Biomedical Sciences: 81 (580)
Clinical Sciences: 99 (730)
Data, Research Interpretation, & Evidence Based Dentistry: 67 (540)
Patient Management: 74 (550)
I don't know how any of this information helps others, but I thought I'd contribute.