The new edition published this year 2016, is exactly like the one that Gordon Wenham published in 2003, with the exception of the front cover. Do not spend the extra money for the 2016 edition if there is a 2003 edition available.
Exploring the Old Testament Volumes 1 and 4 are required reading for my college course in Christian Theology. We have not yet begun to study out of Volume 4, but I have found Volume 1 to be extremely helpful in explaining why certain things were done in the OT Law. I would recommend them to anyone who would like to gain a deeper knowledge of God's Word.