"Unfortunately, the Real ACT Prep Guide only contains 5 practice tests, and in my opinion a student must take at least 6-10 practice tests in order to be fully prepared.
I've been using this book with my ACT students for a few months now, and don't have many complaints. There are a few typos here and there, but for the most part they are very similar to real ACT practice tests."
"The advice, as per usual in most Princeton books, is oversimplified, and the answers to some of the sample questions are too easy or obvious. But the practice tests are helpful if you run out of the other tests.
There are 2 practice tests in this book, and a 3rd test online. Remember that "unofficial" practice tests such as these are generally harder than the real thing."