http://www.davidwesterfield.net/2009/06/the-shack-a-review/
Here are a few subsequent articles:
Shack Author William P. Young Denies Penal Substitution (MP3):
http://www.davidwesterfield.net/2009/03/shack-author-william-p-young-denies-penal-substitution-mp3/
Cursed is Everyone Who is Hanged on a Tree:
http://www.davidwesterfield.net/2009/03/cursed-is-everyone-who-is-hanged-on-a-tree/
The Shack is a Fictional Portrayal of God?:
http://www.davidwesterfield.net/2009/03/the-shack-is-a-fictional-portrayal-of-god/
A Position Based Purely on Emotions:
http://www.davidwesterfield.net/2009/04/a-position-based-purely-on-emotions/