I just finished the 3rd of 3 required texts for my upcoming course "The Christian Spiritual Life." The texts were Renovation of the Heart by Dallas Willard, Spiritual Theology by Simon Chan, and Shaped by the Word by Robert Mulholland.
I enjoyed all three books. I would recommend for all Christians to read chapter first two and last two chapters of Willard's book (this is where he is most passionate and expresses his overall theme best). Chan's book is most impressive in regards to Chan himself. He is one of the most well-read and well-rounded Christians I've ever read. It's hard to believe he has such a grasp on so many different contexts. I just finished Mullholland's book and found it very energizing. I have to admit that I come to the Scriptures most-often in search of information, not formation. His challenge is well received.
Now, even though Mulholland would be upset, I must soon turn to the 6 texts-books for my other summer course!