how similar is it to the actual test? i have the practice book with 6 tests and the math seems very easy. is it just me, or is it supposed to be like that?
Yeah, not very good.
Check other information in this forum. Standard books like that were mediocre before, but are worse after change to new SAT. Use real tests. New books like Kallis and Ivy Global are probably best. I would also Erica Meltzer books for verbal sections and Barron Math SAT Workbook is OK.
i have erica meltzer for grammar and reading (The Critical Reader book) and it’s helped so much! I would say that Princeton sucked. Did not help me much 
My teacher lent me a different PR book.
Some of the questions just do NOT seem to match with the actual SAT questions:
https://www.amazon.com/500-Practice-Questions-New-SAT/dp/1101881755
In general, the book is meh in quality; however, the answer explanations are better than the CB official practice tests. The questions are vaguer and more ambiguous but at the same time easier than the actual SAT.
Here is one:
“Bigelow was born in CA in 1951, and she (rolled/enrolled/unrolled/rickrolled) in the San Francisco Art Institute.”
Would an actual SAT contain “rickrolled” as a possible answer? Maybe “rerolled,” but not “rickrolled.”
Princeton Review is terrible for me. Did not help me at all when studying for my ACT in high school. In terms of tests, I would prefer the SAT ALL THE WAY. Use all available college board materials since they make the test and their help with be the most authentic. In addition, buy Kaplan books. They are a must.