This is a great resource, but you need to be clear on what you are getting. It is not going to teach you any material. That you are going to get from class or textbooks, or both. It is simply a book that will give you all the formulas in one place, in a much more compact form than any textbook will give you. You do not have to weave through pages of proofs, explanations, or examples to get to the end result. It covers things from the very simple to the very advanced. Realistically it is impossible to recall every formula that you come across in math and science classes. And, a lot of times people do not keep their textbooks, but you never know when you are going to have to look up a formula at some point down the road that you know exists, but cannot remember all the details of.
When I was in upper-level engineering classes, the professors tended to keep the math relatively basic for many exam questions, but there were some homework questions and class examples that got pretty detailed, and a lot of times they would just say you can solve this using ________ equation/formula and just assume we remember it. Now yes in this day and age you can find almost anything on the internet, but for those of us who prefer books, and writing out homework by hand, this is a great resource. And if you happen to have a class that gives totally open book/note exams, it is something that could come in handy.