Although I have an EF 28-135mm IS USM for general usage lens, and a good quality 50mm 1.2 for portrait work. I needed a prime lens with some range, but with good DOF (depth of field) only found on short portrait lens'.
The build of the lens case is standard quality, but with a metal bayonette that locks tight, similiar to higher priced L class lens. It's a solid and heavy piece of glass and it's quality is right up there with the L glass. I have a 135mm prime 2 L, a $1300 lens, but too long for a 1.6 crop factor camera as with my 40D. I was relieved to find the image quality of 100mm macro to be on par.
If shooting on a Rebel or EOS 10-40D, having a battery grip will benefit as it's a forward heavy lens.
The design is a few years old, and thus lacks IS (image stabilization), so a tripod, monopod will be required in dim lit churches with no-flash policies.
Autofocus is slow when going from macro to distant, and considering the range, that's to be expected. However, once your close to the focal distance, AF is quick. In some cases you'll have to coax AF to work by manually focusing. A large, wide rubber bezzle makes manual focusing a breeze.
In many cases I switched to full manual anyway, finding it a joy to use.
With F2.8, and it's just enough to get a flashless, dim lit shot with very useable 800 ISO (on tripod/monopod) at 1/100 sec shutter. On and EOS 40d, 1.6 crop factor, the range requires about twenty feet to get a full torso portrait shot, perfect for standing back and not getting in the way of a ceremony, but getting beautiful background seperation.
IS would be a welcomed featured on the next generation lens. But that's not a deal killer.
Being a macro, and having high level DOF, I can't wait for my next product shoot in the studio.
This lens will live on my camera until I need more range or a wide shot from the 28-135. The images simply pop, and I'd rather move back a little if need be to get that.