His work belongs to the German Romantic movement. He was a member of the circle of Heidelberg Romantics. Fries rejected the moody atmospheres common in the era. He preferred clear light and architectural precision. In his series, Six Views of Heidelberg Castle, he documented the ruins with a draughtsman's eye for detail. Pieces like Castle Terrace and Towards Northeast show his ability to balance natural surroundings with the structural geometry of stone walls. His lithographs helped define the visual identity of the castle for early travellers.

Modern collectors value the clarity and calmness of his compositions. His prints, such as Hunting Scene or the views of the Ruffi Mountains, offer a sense of order and historical documentation. The work avoids the sentimental clutter often found in nineteenth-century art. His use of space and light makes these pieces suitable for contemporary interiors. The technical skill in his lithography ensures that even small details of the Baden countryside remain sharp and legible.