The Princeton Review, like any other test prep. company, is a business. If they're offering a free test, I would think there has to be some sort of incentive for them. If they can give you a test and make you feel unprepared for the MCAT, it may may motivate you enough to register for a prep. course with them. Might sound a little cynical, just my opinion though. Based on a quick read through of the link posted by wish2bMD, it seems like others struggled with the test as well. As long as you still have adequate time to prepare, don't panic and just do work.