Here's a few links that might be of interest to you, OP.
Flickr: The Canon EF 135mm f/2.8 Soft Focus Pool
LOL, 4 of my pictures are on the first (most recent) page of that. (I'm J__E on Flickr.)
(Not saying that they're good or anything, but I do have the lens - so I could do some kind of test if anybody was interested.)
Only one of those 4 (the most recent one, and currently the most recent in the group) has the soft focus 'turned on'.
(And it needs to be re-scanned - I don't really like the way it came out, but I haven't got around to doing it yet...)
There are much better examples of that lens on there than the ones by me...
I can dig through my archives and see if I can find some better ones...
(Not exactly my most used lens...lol. Just checked, and I only have 144 pictures from it since 2006.

)
It's not
too bad with the soft focus turned off. Not "L" sharp, or even 50mm 1.4, or 85mm 1.8 sharp, but it's better than the kit lens.

Overall - not a bad lens for the price. I can't remember what I paid for it, but I do remember that it's the cheapest lens I own.
edit - again, lol
OK, here's two pictures I found. Not the best, but of what I have from this lens, they probably show the bokeh the best.
(Only posting them so you can see the bokeh - no C&C necessary, lol.)
Soft focus OFF:
Soft focus ON:
There are 3 soft focus settings on the lens - 0 (off), 1, & 2. I don't remember which the last one was at (1 or 2), and that doesn't get recorded into the exif... Looks like it was probably on 1 though.