It gets a good review for the Sony mount.

http://www.photozone.de/Reviews/47-sony-alpha-aps-c/386-tamron_1750_28_s...

Taken with the Sony A700 and Tamron 17-50mm f2.8

Finally getting around to PPing some of these...
http://www.cramptonstation.com/storm1a.jpg
http://www.cramptonstation.com/storm2a.jpg
http://www.cramptonstation.com/storm3.jpg
http://www.cramptonstation.com/storm4.jpg
http://www.cramptonstation.com/storm5.jpg
http://www.cramptonstation.com/storm6.jpg

This lens seems awfully soft for such a highly reviewed lens. I have only had it a few hours so it could be a learning curve thing though it doesn't seem like it should be this bad. It's sharpest at F8. At F2.8 it's soft and sometimes objects have a ghostly glow to them. In high contrast scenes it exhibits purple fringing at the edges.
100% crops of the center of the image. All shots are handheld.
F2.8
http://www.cramptonstation.com/tamron28.jpg
F4
http://www.cramptonstation.com/tamron4.jpg
F8
http://www.cramptonstation.com/tamron8.jpg