Complex shapes are easier with surfacing
Some shapes just cannot be created with the standard solid model features (extrude, revolve, sweep, etc.). Additionally, advanced solid features, like lofting and sweeps, have a tendency to result in shapes that have one or more flat faces. Surfacing, on the other hand, is frequently used to create geometry that is tangent to edges or has no flat ends. For example, the part shown above is easier to model using surfacing than any combination of solid model features.
Control every face in the model independently
Surfacing builds a shape a single surface at a time. When using solid features, the tool essentially automates the surfacing process and builds several sides of a shape, all at once. The feature that is built has a one-directional flow, which may cause the intended surface shape to become compromised. Surface features, on the other hand, build the 3D model face-by-face, which will allow for multiple modeling techniques and directions to be used on different faces to get the exact shape.
Help! I need a surface!
Surfaces can be used to help build better models. Any type of surface body can be used as reference geometry to assist with modeling or to modify solids. Surfaces can be used to cut a solid body (cut with surface tool), to split a solid body into two or more solid bodies, as construction geometry with the “Up To Surface” end condition, to replace one or more faces of a solid, as well as many additional applications. Go and explore what your surface menu has to offer!