I did use the lens some on my Big Bend trip but after the first day of hiking I decided that it wasn't practical to have both the 70-200VR and the Sigma 150 in my backpack, so I really only had access to the 150 when we were near the car. I did get some shots with it, but I'm not finished going through all my images yet. I should have a gallery up by the weekend that will include at least a few shots with the 150 macro.
My general impression is that it's a nice lens. Build quality is very good. HSM is great, being able to seamless switch between AF and MF is a big advantage IMHO. Optically this is a very sharp lens. Contrast is good also although not to the level of the 70-200VR (to be expected though I guess). Bokeh is only fair, but that's true for most macros because of they way they're designed. Of course with the 150mm focal length if you can put any distance at all between your subject and the background, the bg will be so heavliy blurred that bokeh quality isn't too much of an issue.
In the meantime here's a quickie shot I took playing around with the lens on the side of my house. This is the full frame and I was right at the min focus distance, so this is roughly a 1:1 reproduction.

Full EXIF available here:
http://www.pbase.com/image/41486232