As for using it for portrait, florianbieler.de has a couple of nice examples on this thread page from the Lens Gallery:
Hey thanks for pointin' me out
I also played with the 135L a bit, definitely also a very desirable portrait lens and even another tad sharper than the 100L. As I couldn't really afford both I sticked with the 100L because the difference is not that big (also not bokeh-wise) and you got IS and Macro on top. I say if you can afford both, get them both but if not then think about if you need IS and Macro. When you only want to do portrait and that mainly from a tripod, get the 135 instead.
The 100mm macro has harsh bokeh past macro distance. It should never be chosen as a portrait lens.
Well that's just rubbish. Throw your face at my shots with the 100mm and show me "harsh bokeh".