Pretty good macro lens.

Configuration.
I use this lens on a Nikon FM camera body. The lens has an auto-focus capability however since my Nikon is <old> I use the lens in "manual" mode. This is not a big deal; I just have to manually focus / manipulate the f-stop.

Build.
The lens is solid and there is nothing unexpected in terms of weight. (the lens seems a bit heavy, but it is a macro lens after all) With my particular Sigma lens there is an odd sort of grating when I rotate the focusing ring -- kind of like bearings rubbing harshly. The turning mechanism is quite loud too. This is probably due to the fact that I am using it in manual mode. I have not tested the lens on an automatic SLR to determine if this is the case.

Picture quality.
Not bad. The pics arent as sharp as I would like but you have to keep in mind this lens was at such a reasonable price that I had to expect that it would not incorporate "all the bells and whistles." Because it is a macro lens lighting is critical to obtaining a good shot. With the lens protruding nearly all the way out of the camera, you will be about 1 or 2 cm from the subject. This does not leave much room for getting sufficient light onto the subject.

Verdict.
I would consider another Sigma lens if I had a particular budget to maintain. I think the prints I obtain from this configuration is sufficient for an amateur but a professional might expect more.