I own the Canon lens (on a 400D camera). Rather satisfied, but it is not an inspiring lens.
I refer most of all to image quality. I know Sigma has some more focal length and it is a good thing obviously. As for wider aperture I don’t know if it has any value.
Is the Sigma worth it, considering that the Sigma costs (as of October 2012) about 300 euros more (which incidentally I could use to buy a GF2 with 14mm lens)? Is there a considerable improvement in image quality and general performance?
What other alternative for a standard zoom should I consider?