I give this book a 4 for the following reasons:
-it's one of the most comprehensive guides to exploring your own giftedness, 'spiritual gifts' or otherwise
-it highlights that natural abilities and acquired skills are an equally valid part of our giftedness and who we've been created to be
-it gives thoughtful explanations of spiritual gifts as listed in Scripture, with examples and 'symptoms' of each gift
-it has experience and conviction questionnaires to help parse out what your desires are and what you would enjoy based on your experience
-other books aren't as thorough.
Downsides:
-editing is nonexistent. He has a good reason for not having an editor, but it can make it hard to read. Generally, formatting is functional.
-written by two engineers - it has an 'instruction manual' feel