Igor Grabar praised Brenna for an extreme degree of naturalism in his artwork and considered Brenna to be the watershed between naturalism of the 18th century and stylization of Empire style. Nikolay Lanceray, who wrote a biography of Brenna in 1935–1938, called Brenna "the last spark of 18th century art" and noted that his naturalism resurfaced in the middle of the 19th century, but the eclectic architects of this period failed in reproducing Brenna's wholesome realism; only Rossi managed to combine the virtues of Brenna and Quarenghi. Lanceray noted Brenna's weakness in floorplan designs, labeling them "helpless and primitive", and praised him for nearly perfect facades of Saint Michael's Castle.