Müller was a skilled engraver who prioritised clarity and technical precision. His portraits, such as Portret van Nicolaus Christoph Lunker and Portret van Johann Georg Ritter von Zimmermann, demonstrate a disciplined use of line. He avoided unnecessary ornamentation. Instead, he relied on the stark contrast of the print medium to define his subjects. His work sits within the tradition of German printmaking, where the accuracy of the likeness was the primary objective of the engraver.

Collectors today value the historical record found in Müller's prints. His depictions of early 19th-century figures provide a direct link to the intellectual and military history of Germany. The monochrome nature of his engravings allows these pieces to fit easily into various interior styles. They offer a sense of order and historical weight. The prints are appreciated for their straightforward composition and the way they capture a specific moment in European history.