His technique relies on a disciplined use of line to create volume. In works like Portret van Antonio de Tassis and H. Catharina van Alexandrië, Neefs uses hatched lines to build form instead of soft washes. This approach was effective when he collaborated with the workshops of Peter Paul Rubens and Anthony van Dyck. He translated their fluid painted strokes into the rigid medium of copperplate engraving. His prints maintain a sense of structural logic. Every mark on the plate defines the subject with intent.

Modern collectors value Neefs for the graphic strength of his compositions. His work avoids the cluttered ornamentation often found in Baroque prints. Instead, he focuses on the human figure and the clarity of the pose. Prints such as Coridon en Sylvia or his portraits of bishops provide a window into seventeenth-century Antwerp through technical mastery. These engravings suit contemporary interiors because of their monochromatic palette and their formal quality. They offer a sense of history without the visual noise of more decorative styles.