Others say...

"A real gem of a lens"
I've owned this lens for about 5 months now, and it is exceptional. Sharpness and color rendition are spot on and it is difficult to imagine any improvement (this lens really is tack sharp, it is a bit sharper than the 600mm IS). The extra 50mm on top of "typical" 100mm macros provides needed working distance with skittish insects. AF is quick (for a macro), silent, and accurate (for a macro). It even doubles as a pretty good tele, except that the focus speed cannot compete with a real tele. All macros are this way since the focus speed is compromised by the need to rack out the optics far enough to focus at 1:1. Does portraits too, though your subjects might find the optics to be a bit too sharp for their liking.

The focus limiter is a thoughtful and useful touch, as is the tripod ring. The build on this lens is excellent and it feels like a tank. Friction on the focus ring is perfectly damped which is especially important for a macro lens. The finish is nice and has held up to some heavy use (which is surprising since the same has NOT occured with the 50-500mm Bigma). No complaints at all with this lens. I recommend this lens over all of the ~100mm competitors due to the extra 50mm of reach, especially if you work with insects.

"I have to agree..."
Sigma has hit a home run here. This is a nice macro lens, and also serves well as a short tele lens. Set the limiter and let the fast ad quiet HSM focusing work for you in tele-mode. In close-up/macro mode, the AF is less useful (but can often get you close to where you want to be quickly), then fine tune manually. Images are SUPER sharp, good color, excellent bokeh. Excellent price, and EX fit and finish is superb. Very very highly reccomended.

"Sigma 150mm f/2.8 Macro lens"
great lens and a great price. it has a nice feel to it. not too heavy and not too light. autofocus is somewhat slow but that is expected from a macro lens. otherwise its a great lens

"Sigma gets an A on this one."
I have the Nikon 60 Micro lens and wanted something with more working distance. In the Photozone.de test, it was amazing. Very high resolution, even at f/2.8. And very low CA's(chromatic abberations). So I bought it and does it deliver that kind of performance? Yes it does! Sharpness and color redention was stunning. And at 1:1(life size on the negative or digital sensor), there's more than 7 inches working distance. Build quality is excellent. It's mostly metal construction. The focus ring has a nice dampened feel to it. The new Sigma rear caps fit tighter and do not come off. But they're a little harder to mount. About autofocus performance, it's fast, but hunted in low light with the Nikon D50 while shooting motocross. But that's a weakness of the camera body, not the lens. On the F100(a high end Nikon film camera), it was lightning fast and dead on. Yes it is a full frame lens, so it can be used on 35mm cameras also. There's a tripod collar and it makes for a well balanced setup when on a tripod. The collar is removable making it easier to do handheld shooting. The maximum aperture of f/2.8 allows more flexibility in low light. The filter thread is 72mm, and filters this big get expensive. It is a good all around telephoto-sports, portraits, landscapes...you name it. Just because it's labeled a macro doesn't mean a lens is good for macro only! It's not cheap, but if you want a solid performer that's great for all occasions, this just may what you're looking for.

"AWESOME LENS!"
This lens is fast and extremely sharp. I am using it on a D200 and it is great. I am deployed in Iraq and this lens is one I can feel comfortable about walking around with. It's built like a tank. It accepts the teleconverters which makes it even better. Buy this lens from 47th St Photo. Best prices.