This is a great general purpose Macro lens.  It's small enough to hand hold, and at f/2.8 it's fast enough to work well without a flash most of the time.  The autofocus is quick and accurate, and you don't necessarily need to focus manually as you do with some Macro lenses.  Due to having floating internal elements, the EF 100mm has a shorter than 100 mm internal actual focal length at 1:1 - it's around 70-80mm - which means you can maintain a good field of view whilst getting a very useable 15cm of Working Depth for Macro shots.

And of course, as you'd expect for a Macro lens, the 100mm f/2.8 is superbly sharp.  It functions well as a short telephoto lens, and many people use it as an alternative portrait lens.