I love John Holland! For being a medium, he has a very down to earth approach to explaining different experiences that occur in his work. Often when I listen to different spiritual teachers try to explain things, I tend to think they're from a different planet. John Holland definitely has a beautiful way of explaining the phenomenon of his medium-ship experiences and helps me feel better about this type of work. I love the fact that rather than having an attitude of " of course it's real you just have to believe" he encourages people to be skeptical of this type of work and wants people to be open to their own powerful spiritual experiences.
John has a very positive and enlightening point of view, bringing in lots of love to the world of the deceased as well as the living, and helping us remember that there is nothing to be afraid of. In this book 'Spirit Whisperer' John explains a little bit about his experience being trained as a medium, some of his personal experiences both teaching and with private readings he's had or given, and also has chapters dedicated to signs, reincarnation, animals, etc. I found most of this book covers John's personal experiences and what he has learned and gained from them. If you're into mediumship at all, John Holland is someone definitely worth looking into.
Another book I would recommend from John Holland, if your into spiritual/psychic phenomenon is Power of the soul where he explains several different alternative tools you can use to help you open up to greater spiritual understanding.