This one-legged exercise targets the quads, glutes, and hamstrings directly, while indirectly training core stability and balance.
By lifting one of the legs, and unstable demand is placed on the hip of the working (squatting) leg. This requires lots of coordination and balance between the muscle surrounding the joint.
At the same time the unstable nature encourages greater core strength. The benefit is balanced muscular development which not only looks better but helps promote better performance for most sports involving running cutting or jumping; not to mention making daily activities easier.
The great thing about this exercise is it is a simpler version of the unsupported pistol squat making it easy for anyone to implement into their program.