Mr. Nordsieck relies heavily on redaction-, form-, and tradition-criticism and argues against the current in German scholarship to perceive the Gospel of Thomas as a Gnostic text. He thinks that the text represents a form of Jewish Christianity. He also says that the Gospel of Thomas potentially can tell us about the historical Jesus, and should not be dismissed in these discussions. In fact, he doesn't think that a good reconstruction of the historical Jesus or New Testament theology is possible without reference to Thomas.
His book starts with a bibliographical introduction (27 pages), a short discussion of the historical Jesus (8 pages), and ends with a substantial saying-by-saying commentary (361 pages).