I purchased "The 7 Habits of Highly Effective People: Personal Workbook" to accompany the regular text, "The 7 Habits of Highly Effective People". Using the two books together has been very effective for me. The workbook lets you know which pages of the original book to read before completing its exercises. The activities it asks you to carry out help to extend the messages of the habits, and it offers practical suggestions for how to apply the habits (and self-reflection) within your own life. Unless you were very familiar with the 7 Habits, the workbook wouldn't be too good on its own though. Covey's writing is enjoyable and clear, and in my opinion steers clear of being saccharine quite nicely.
If anyone wonders what exactly the 7 Habits is about in the first place, it is largely concerned with changing one's principles and negative habits in order to bring about happiness and success. (By which I mean lasting, deep happiness, and not temporary satisfaction). If you have an inherent sense of morality and good (whether religious or not), and a belief in your ability to constantly improve, then give it a go!