Only four volumes of this set are in print. The other six are rare and hard to find, but I've found most of them through secondhand shopping online.
Volume One: Genesis-Exodus. This volume has an introduction to the set, and then his explication of the main themes of Genesis and Exodus. This is not a commentary per se, but rather a retelling of the narrative so that we can grasp the broad arc of the story. It was very helpful in this regard. He has very few missteps in the text. The biggest thing for me was constantly harping on the patriarchs for supposed sins that aren't really sins (just read James Jordan, Primeval Saints). But then Van der Waal was writing before Jordan, so we can't really blame him. He writes from the refreshing perspective of Dutch Reformed theology, and so rejects the law/gospel divide, the faith/works divide, and emphasizes the unity of the Bible and the unity of the covenant. Great stuff.