I've read the entire trilogy... The Celestine Prophecy, The Tenth Insight: Holding the Vision, and The Secret of Shambhala: In Search of the Eleventh Insight. I enjoyed them... though by the third book I found the premise very worn out. Definitely typical new age squishy. If you enjoy James Redfield, you'd probably also enjoy Dan Millman's books:
Way of the Peaceful Warrior and
Sacred Journey of the Peaceful Warrior.