In order to prepare for the JLPT3 exam, I purchased this book to see what my weak points were. I found the mock tests here good simulations of the real tests, with the right distribution of kanji, grammar, listening, and reading comprehension. The book comes with a CD for the listening section, which is well-produced and definitely challenging.
The best part of the book is the answer section in the end which goes over each questions and why a certain answer is correct. For the listening section, they print a dialogue so you know what exactly they said with the key points highlighted. The end of the book also comes with a nice analysis of your score, and tells you what to practice if you get certain questions wrong.
This is highly recommended months before you take the JLPT3 because it will give you helpful tools to correct your mistakes and give you a better framework on what to prepare for. Definitely a wise purchase.