Thanks dryan for the video! My own experiences are quite the same.
To get an impression what kind of dreamy effect the sigma delivers in the near field, I've uploaded a 50% size sample shot from photokina - its clearly visible, even more so at 1:1 100%. This JPG ist OOC, shot was taken around the max. mag. distance of that lens.
If you increase the distance, the glowness is reduced and remains visible mostly around highlights. Nevertheless, it's still there even in the shadows, visible by the overall reduced contrast:
In the far field, the picture looked ok, but lacked the punch that those of the tamron had. There mighht be a small backfocus on this lens as I aimed for the wheel and the brakedisc seems sharper, but overall I wasn't just impressed with the results I got (org. full size file):
Build quality was better at the sigma in terms of surface feeling, it just felt "metal". But as I know how fast this EX finish collects dust and dirt and just gets splotched, I'm not very keen on this finish. However, having a metal outer shell does indeed suggest some kind of reliability.
The first impression of reliability disappeared in the first use: the AF pumping often discribed in various resports, appeared in a lot of test framing I did. It apeared only once on the tamron and that was on the very first target I aimed after the lens was mounted on my own S5 (btw, thanks for the exception of the rule, Tamron team).
I returned to the tamron stand a second time to test the tammy on some other bodies because I was in the market for a 70-200mm lens and my visited to photokina was dedicated to testing the options available. I also took testshots on the Nikon VR, which is an excellent lens. But those of the tamron where really good, regarding the price and my lack of need for an AF-S drive and IS, the choice was easy.
I'll give you an update ont he lens as soon as I get it, propably on tuesday.