A giant leap forwar for Sigma.
Having owned the previous version of this lens I was expecting decent performance but nothing spectacular. In fact this lens is really truly sharp wide open by any measure. Like the Canon 70-200 II it genuinely rivals quality prime lenses for sharpness.
OS seems to live up to its billing and build quality is night and day compared with its predecessor-it really feels like a quality product. It focuses just like a Canon L and so far tracking seems accurate too. Results with a 1.4XIII are superb. Great value and a 3year warranty but it would be a bargain at twice the price IMO.
It's heavy (but still manageable for hand held use). I suppose a titanium body is too much to ask at this price point!