From Amazon reviews:

The simplified, incomplete gospel according to Mitchell, June 7, 2002
Reviewer: Nathan Kitler - See all my reviews

If you want a book that explores which of Jesus' sayings are really authentic, look elsewhere: Mitchell is so wrapped up in being P.C. and "spiritual" that he turns this book into a mixture of misinformation and half-truths. Another caution: Mitchell is not concerned with God in any Judeo-Christian or even theistic sense of the word, only as another "reality."
For starters, as it has been pointed out in reviews on Mitchell's other book, "The Gospel According to Jesus", Mitchell's criteria for deciding whether a saying attributed to Jesus is authentic or not is whether it sounds right to him! How unscholarly and self-centered can you get? In the introduction he compares what he is doing to Thomas Jefferson's version of the gospels (which leaves out the Resurrection entirely) except that "unlike him, I was able to use the precision tools of modern scholarship. I also used the spiritual intuition that I had deepened over many years of Zen training. I selected and translated only the passages that seemed to me authentic accounts and sayings of Jesus, and I left out every passage that seemed like a later addition." (xxiv-v) Listen to him! Does he really consider that a better method than Jefferson's?

The biggest flaw is that Mitchell is quite haphazard in documenting and citing biblical passages. One example of a passage: "The kingdom of God doesn't come if you watch for it. It isn't in heaven. It doesn't come only after you die. No one can point and say 'it is here' or 'it is there.' For the kingdom of God is within you." (22). This should be from Luke 17:20-2, except it doesn't say "It doesn't come only after you die." This is a belief Mitchell would like the reader to believe, closer to Buddhism than biblical Christianity. In many places Mitchell forgets to indicate where the biblical text ends and his own opinion begins, which unscolarly and dishonest. Also, not every biblical passage in the book is cited, not even in the notes at the end of the book. He even disregards how much of the New Testament is directly from the Old Testament. People who want factual evidence to study, shun this book.

If you want to decide whether this book is for you, skip to the Afterword: "The authentic Jesus, as I see him, was not a divine being (whatever that means), born of a virgin mother, surrounded by angels and wise men, and essentially different from all other humans. ... At the age of about thirty, he had an extraordinary experience of waking up to the truth. ... He was a man in love with God, who gave himself completely to the acts of human kindness that proceeded from that love. At this point you may be thinking, 'Jesus teachings sound wonderful, but what good are they? What do they mean for me? ... How can I love bigots and racists, for example? ... These are questions people have been asking for thousands of years. The fact is that no one, not even the greatest teacher, can show you how to love. A teacher can point you in the right direction, but that's about all. 'Some say my teaching is nonsense,' Lao-tzu says in the Tao Te Ching... But how do you look inside yourself? One way is meditation ... Another way ... is called the Work of Byron Katie. (NOTE: she is Mitchell's wife! To me, he's just offering more of the same) Whatever method you find, when you're able to look inside yourself deeply and understand your own mind, your life will become more peaceful. ... So the best way to follow Jesus' teachings is not to follow them at all but to live them. When you're able to look inside yourself deeply, you'll find that the teacher who taught Jesus will teach you. That teacher has no name. It is closer to you than breathing, nearer to you than your own thoughts." (109-112)

I should point out that Mitchell gets some of the historical points in Jesus' life correct, mainly that he was a Jew and crucifixion was a horrible way to die, but that's about it. Mitchell's Jesus might as well be another new-age teacher. Ultimately, it seems to me, you can search for truth either inside or outside yourself. If you are flawed, then what you find within yourself will also be flawed. As for contributing to my search for truth, I was disappointed by this book.