I took it last year and thought it was probably the most difficult/weird/frustrating exam I've taken in the field of medicine. I'm not sure how I passed.
Passed...I used the following:
(1) Klein and Asher Book (excellent source, videos are representative)
(2) Went to ASE Board Review (the syllabus handouts from the physics and congenital/peds lectures were excellent)
(3) Purchased access to the "ASCeXAM/ReASCE Online Practice Exam Simulation" (questions were very similar in content to the actual exam)
(4) Completed physics questions on Sidney Edelman's site (granted access after going to ASE Board Review)