There's been a lot of buzz about The Shack lately, and although I haven't read the book, I thought I would use this semi-public platform to make some information available.
From the commentary I've read, it's my opinion that there are some serious red flags with this book, and that Christians should be cautious about their response to it.
Here are a couple of good links for further info:
In-depth review from Tim Challies
Pastoral perspective from Pastor Walter Price
Or, if you like video reviews, here's Mark Driscoll (keep in mind that Driscoll is talking specifically about potential heresy concerning the Trinity):