Originally Posted by NickTrop
Nobody cares about "bokeh" except wonks. This is especially true of focal lengths 50mm and shorter. "Bokeh" is simply used to draw attention to the subject. Only amateur photographers concern themselves with bokeh in this range. Normal -- wide focal lengths aren't about that. If you want to blow out the background into a painterly abstract mess of colors, close focus at 85mm+ and don't worry about how fast the lens is. Nearly any aperture will suffice and any lens in that range will do. Get a cheap off-brand 135/2.8. Sears, JC Penny, "Imado", Spiraton, Vivitar, Tokina -- whatever, off the auction site. Nobody bids on them. Bokeh city, all.
Well, the background in the picture above your post, by Petronius, looks odd to me. But that may be mostly due to the stripes and/or an unluck distance. I think that most lenses can deliver good-looking oof backgrounds and worse ones, depending on distance, background, lighting, aperture etc. and in the big picture it doesn't matter much, it hardly makes or breaks an image.
However if one has the choice between similar lenses, all sharp and affordable, it's a criterion as good as any.