This zoom lens from sigma seemed ok for myself,admittedly a bit of a novice in photography, it has a reasonable range , however it did seem a little slow on the zoom , not to mention noisy, this is in comparison to the zuicko lens I have which covers a similar range. Pricewise its reasonable , but I would imagine its use is limited.
I wanted a general lightweight walkabout lens for my Sony A100. I read about this zoom lens and found a new example on eBay. After testing it, I found it to be a really decent performer in all departments. Not exceptional, though competent.
No real major bad points. Images are clean. As with the Sigma 70-300mm APO DG Macro, the AF can 'hunt' a little at times, which appears to be a trait of the brand.
The zoom is fast enough and the Bokeh is also nice. Colours can be a little 'contrasty', but adjustable in pp.
I like it . . surprisingly . . fits my requirements perfectly as a general walkabout lens.
Maybe a little hidden gem! I'd give it 85/100 at this stage.