I mostly agree with Brenda, but it does not include a lot of instruction so it is what you do with it that will count.
The general suggestion is to take the first test as the SAT is taken, morning, all in one gulp.
After that take one test section a day and go back and look up what you did wrong and figure out why your answer is wrong, why you got it, and how to get it right. At some point, take another all in one gulp test and see if you are improving.
I agree with Candid, here, too. If that first SAT run-through turns up some specific weak areas, it might be worth using another resource to bolter those areas before just continuing with testing practice. I used Chalkdust SAT Math review with my oldest for certain math concepts. I used College Prep Genius with my next one for overall SAT strategy advice, and that helped a bit, but he didn't follow their recommended techniques to the letter. He did get some valuable insights on test-taking strategy, though.
I still think that nothing helped prepare him better than just working through the CB tests and carefully reviewing the answers. Doing this definitely helped him to start to see particular types of questions, especially in the Critical Reading & Writing sections.