This is a pretty large lens – one I’d recommend using a tripod with unless you’ve got excellent light, strong hands, and great technique. Other than that though, it’s an amazing lens. At 180mm you can get a lot of distance between the lens and the subject, which can be important for some types of Macro shooting.

The long focal length also tends to make the background more blurred, which really isolates the subject from the background. It is, however, a specialty lens, so unless you’re a dedicated Macro shooter, you’d probably be better off with a Canon 100mm f/2.8L IS or Sigma 150mm f/2.8 Macro and a little less size.
March, 2013