I've just finished reading 'The Shack' by William P Young. I enjoyed it very much. Someone from my Bible Study group lent it to me - she couldn't believe I hadn't heard of it. It's basically a sort of theological metaphor or allegory. Eugene Peterson compares it to Pilgrim's Progress in the quote on the front cover.
The author has really done a good job - I can be very critical of intellectual consistency and this book stands firm. I love his characterisation of the three persons of the trinity. It would be great to use this book in a Bible study and pick up each theological concept, studying the scriptures that relate.
I'm not sure that I agree 100% with his theological viewpoint - I might shift the emphases. But then again I might not. Definitely a book that is worth reading.