That's pretty disappointing for a 'legendary' lens and following hard on the heels of the 16-50's poor showing on this forum.
I'm sorry, but the photo above looks washed out and lacking detail. Maybe this is what makes it great for portraits? The sample photos on Lenstip were equally low contrast and hazy with awful purple fringing.
Have a look at the top right corner of the above photo - it's soft and a purple smudge, and that isn't even the true top right of the lens - it's designed for full frame, so goodness knows how bad it must really get on 35mm?
Robert Donovan did a posting with a comparison between the FA31 and DA18-55 -
DA18-55 looks pretty decent by comparison.
Another point that should be raised - why can Sigma make and assemble lenses in Japan yet they're cheaper and with modern designs, better coatings and frequently have exotic glass like flourite included in the design? Pentax's are made in a third world communist country where workers are poorly paid and have little in the way of rights. Yet Pentax's lenses cost more? Where's the difference going? Here's hoping Ricoh return Pentax to Japan, or at least ensure work and quality matches Japan. Sigma proves that doesn't mean higher costs to lens buyers. Seriously time to do something about modernizing some of the lenses to match the excellent performance of the bodies.