I wil begin this post with another citation from Sulzbach:
In order to construct a scholarly and credible refutation of the Protestant biblical scholarship of his era. He [Hoffman- W.] had to acquire the necessary tools. First and foremost mastering languages. The basic curriculum for any Jewish Bible scholar required a thorough knowledge of biblical, mishnaic, and medieval Hebrew and Aramaic. to which Hoffmann also added Syriac and Arabic. Of course he worked in German, and as part of his secular education he learned Greek and Latin. Moreover. it should be noted that he indeed utilized the extra-biblical sources these languages provided (Josephus. Philo. LXX. Peshitta and the Samaritan Pentateuch to support his arguments.
His linguistic knowledge alone gave him a great advantage over the Christian scholars, who definitely lacked his virtuosity in Hebrew and Aramaic language and literature. They also lacked much of his insight into Jewish historical and religious dynamics, and thus had to forego the rich information available in other Jewish primary sources. This assumes they were ready to take these sources seriously, but this may be false, as in their opinion, Judaism had lost its right to exist after the rise of Christianity.
Moreover. Hoffmann in fact studied all the attacks upon the Hebrew Bible and Judaism. which enabled him to tight the war on the enemy's ground. Despite Kipling's famous dictum. that East is East and West is West and never the twain shall meet. Hoffmann broke the silence from the Jewish side and did not just go on the defensive with his refutation of critical biblical scholarship. but actually opened up an offensive by using the same methods and reasoning as did the critics. Up to the period of the revival and modernization of'Orthedox Judaism in Germany, of which he was one of the great champions. it had never before happened that these two worlds - which were so far apart - met on equal ground in the pages of a modern. scholarly Jewish commentary on the text of the Pentateuch.
It is to these commentaries I turn now as the 2nd positive aspect fo Hoffman's biblical scholarship. There is already a fairly complete list of articles on R' Hoffman's method of parshanut, as well as links to a hebrew translation his commentaries on Bereishis and Devarim that are available online at Hebrew wiki. (and see example 1 in this article.) It must be noted that these last two commentaries were censored and many of the polemics against the critics were taken out because "nobody is worried about this anymore". (Something similar occurred to the 1965 edition of Shadal's commnetray on Chumash - perhaps for the same reason. See this comment by Dan Klein .)
Personally, I have not used Hoffman's commentary very much. I have a copy of the Hebrew translation of "Das Buch Leviticus" but it is almost entirely unreadable being filled with references to scholars whose works are no longer studied. For the moment, this quote from NEJ must suffice to explain why I refer to this aspect of his work as "positive":
"In his commentaries to Leviticus and Deuteronomy he relied on rabbinic homiletical and exegetical interpretations for an understanding of these books, as well as offering his own innovative ideas, often based on comparisons between biblical Hebrew and other Semitic languages."
 R' Klein's translation of Shadal's commentary comes highly recommended. Especially valuable are the notes since Shadal likes to send us to his articles in Bikkurei Ha'Ittim and Kerem Chemed which are very difficult to obtain. (Some pages of the translation can be seen here.)