In my humble opinion, UPCAT reviews are a waste of money (and time). The UP entrance exam is basically stock knowledge and common sense. If you don't have the required knowledge, principles and ideas ingrained in your mind by the time you're in 4th year high school, I'm sorry, but you will never learn them at review sessions. One is either bound to pass or fail the UPCAT, no matter if he busts his ass at a review course or not.
Of course, review courses aren't a total waste of time. Other university entrance exams are greatly helped by studying. ADMU's, for one, feels like final exams for 4 years of HS. While really smart people can still probably get by on what they remember naturally, intensive reviews (especially on core subjects like Math, Science and English) would definitely boost the chances of those who aren't as gifted.
So I guess my advice would be, if someone is keen on paying for review courses to prepare for university or college entrance exams, it's more worthwhile to sign up for one geared for Ateneo's rather than the UPCAT. Although, really, if your high school offers free reviews (and I think most do), then just go to those! It's one's own efforts and skills that will determine success, anyway, not the review centers'.