How much work should a reviewer do?

There is one last lacuna that demands mention. When Verene puts forward the idea, to cite but one example of many, of the importance of Goethe and the opportunity for a separate study on Goethe's influence on Cassirer, one wonders why Verene has not mentioned John M. Krois who, it is well known, has always insisted on the importance of Goethe for Cassirer. The footnotes of Verene's work are filled with such lacunae.--From this review.

I liked this review a lot; it first offers a critical summary of the book and then moves to substantive criticism. But the last paragraph (quoted above) left me dissatisfied. Rather than just pointing at at an example of "such lacunae," I would have preferred a more substantive list of examples and references as a guide to (future) graduate students and scholarship. But maybe that's too much work to expect from a review? What do readers think?