I am not a huge fan of Lucado, as many are, but I truly enjoyed this book and learned a lot from it. This is an older Lucado book, written in 1997. The basis of The Great House of God is the Lord's prayer. Max takes the prayer apart assigning each part as a room in a house. As we wander through each room, we see how God has created a home for our heart and meets all our needs as we pray His model prayer.
If you want to take your prayer time to a new level, this is a great place to start. I do recommend that you work through the study questions and activities in the back of the book. They add so much! There are questions of introspection, questions that basically review what you have read, digging into the scripture to go deeper and some practical application.
This would be an easy book to read hurriedly, but don't do that. Take your time. Work through a chapter at a time... reading... praying... doing the study portion... let God speak to your heart as you learn more about communicating with Him.