I read this book during the previous month of my boards, it was helpful for me. Mostly question pattern is similar to last years. If you can go through the last year solved question papers section properly, one can easily score 60 percent, and if you are average or good student, chances increase to 80 percent. It’s like a crash course with all the important things you need to remember.
The xam idea for biology helped me in 12th boards too. I can’t speak for the rest subjects but 10th science and 12th biology is good. For last moment preparation, one should straight away start with the solved question papers.