Definitely worth it. I upgraded from the 100mm Macro USM and this lens has made all the difference in the world. The advantages the L has over the 100mm macro USM are manifold: IS, of course, which helps for everything (close-ups outside the macro range), portraits, medium telephoto landscapes, etc; but the real benefits come from improved color, contrast and clarity over the older USM lens. The focusing ring has a much better feel and slightly longer throw for more precise manual focus. The 9-bladed aperture gives much better background blur. AND it's weather-sealed, as well. The price has been drifting lower and Canon refurbs make the choice a no-brainer. Go for the L!