Just in case you aren’t a regular visitor to Challies.com (which you should be!), I want to direct you to his book review of The Circle Maker by Mark Batterson. This book is extremely popular, and I’ve heard a number of serious criticisms about it.
Tim Challies is an excellent book reviewer and he wrote a couple days ago about this particular book saying: “The book has been widely-praised and has received hundreds of positive reviews, but surely people have simply failed to understand that Batterson has committed a grave error.”
Go read it and you’ll find out what that “grave error” is. Challies also offers a list of better and more Biblical books on prayer at the conclusion of his review.