I have the science books and I LOVE them. I find their passages extremely helpful, especially organic and physics (which I was taking in school when I got them). But you need to know how to use them I think. They don't sugarcoat things or give you cute cartoon creatures. You get clear reasoning on how to answer a question by either process of elimination or by knowing enough key points to zero in on the right answer. They also like to mix different subjects together and while I love that, I can understand if you prefer to compartmentalize information, it may be frustrating. I'd suggest a few things to get the most out of them.
(1) Keep a running list of their shortcuts as you work through each chapter.
(2) Do the Phases in order and don't do the practice tests at the end of the books until you've done the entire book.
(3) Pay close attention when they discuss the logic behind the wrong answer choices.
(4) Do ALL of the questions in the reading. There are hundreds, but they are very good at getting the basics. Once you get to the passages, it gets harder.
(5) Don't get discouraged and quit because they are hard. It gets better as you go. There are easier materials out there, but easy practice won't make you better.