In comparing gimbaled versus strapdown INSs, each displays it's own advantages and disadvantages. Perhaps a gimbaled INS's primary advantage is it's inherently lower error. Since it's three orthogonal accelerometers are held in a fixed inertial orientation, only the vertically oriented one will be measuring gravity (and therefore experiencing gravity-related errors). This is in contrast to the strapdown system, whose accelerometers all move and rotate about, each experiencing the acceleration of gravity (and the subsequent errors). Another gimbaled system advantage is the simplicity of its gyros: gimbaled system gyros' primary function is to spin, to maintain a high moment of inertia, whereas strapdown gyros need to actually measure the subtended angles of motion.
The strapdown inertial navigation system's main advantage over the gimbaled system is the simplicity of its mechanical design. Where a gimbaled system requires elaborate and intricate mechanical structures for its gimbals, pickoffs, and low-friction platform connections, the strapdown system is entirely fixed to the body in motion.