p.1 #3 · Sigma 70-200 mm f/2.8 EX DG APO OS HSM review
I tested one myself in a shop yesterday and I was surprised how good it was.
Not exactly Canon-mkII-good but I couldn't find any flaws that made me think "500€ extra for the Canon are really worth it".
Yes my first choice would have been the Canon - it is simply an amazing piece of glass - but if you are not a professional and on a budget the Sigma is the first real alternative (OS and HSM). And a good one.
