I received my Sigma 70-300mm AF Macro lens today. It was $147 from Overstock.com. For the price, it’s a good choice if you need a macro lens or an extremely long zoom. I got the non-motorized model, so AF won’t work on low-end cameras like the D40 or D60. The motorized version sells for about $30 more.
The major drawback of this lens is the extremely slow and noisy auto focus. It often seeks through the entire zoom range to focus. The lens has a macro switch providing 2x magnification, which can only be used above 200mm focal length. The lens doesn’t have an auto/manual focus switch, so you’ll have to use the M/AF switch on the camera body.
The lens feels very hefty and seems rugged with a rubberized surface. Mounting it on the camera can be a bit difficult, since it’s hard to grab it in an area that doesn’t rotate for focus or zoom.
The macro mode gives a very narrow depth of field with good bokeh.