The Samyang 100mm F2.8 ED UMC Macro ($599) comes in at an attractive price point when compared with many other autofocus macro lenses of similar focal lengths, and it's plenty sharp, especially at the narrower apertures used to achieve a reasonable depth of field when working at high magnification.
Quite sharp when stopped down; 1:1 magnification; Internal focus design; Compact; Available for multiple systems; Long focus throw; Attractive price point
Some edge softness at wide apertures; Manual focus design is not for everyone; Omits optical stabilization