I recently read The Complete Idiot's Guide to the Catholic Catechism by Mary DeTurris Poust with theological advisor Fr. David Fulton STD, JCD. Like other books in the Complete Idiot's Guide and Dummies series they present a subject on a beginners level in a somewhat lighthearted way.
Since this one is on the Catholic Catechism itself it is really an introduction to the Catholic faith for beginners along with and introduction explaining the Catechism and the format. For many the size of the Catechism of the Catholic Church is daunting and some might find the language used to be difficult so there will always be a place for a smaller catechism. I remember when I first came across a small catechism at the library written by a source I don't remember, though the experience of reading even these short explanations of the Catholic faith had quite an effect on my life and got me to accept some sins that I up to that point I would have rather have not learned were sins. So I can certainly see how important even a shorter treatment of the Catechism can be.
I found the Complete Idiot's Guide to the Catholic Catechism to be totally in conformance with the Catholic faith and presented the faith quite well. There are plenty of sidebars to further explain words and concepts likely to be unfamiliar to the reader as is common with these types of books. It is also written in a manner easy to read and she uses some humor in her explanations. Though she does not let the humor get in the way and mainly keeps to explaining the various paragraphs of the Catechism. As you would expect there are paragraph reference numbers to the Catechism throughout the book.
I found the book to be a quite useful addition to the number of books concerning the Catechism and I think good orthodox books that serve as an introduction to the faith are always useful. There are only a couple of places in the book where I might have wanted something worded a bit differently, but really nothing to the point where it was in real error. She does make the quite common mistake of thinking the Pope charism of Papal Infallibility to be rare when the fact is it is exercised at every canonization.
There is also another book with a similar format called Catholicism for Dummies by Fr. Trigillo and Fr. Brighenti. I have heard a lot of great things about this other book, though I haven't read it myself yet. Regardless Mary DeTurris Poust book is an excellent entry into the field and one I can recommend to those looking for a solid introduction that is also light reading.