I was just wondering about this lens. I have heard it is not the greatest. And I am finding that a lot of my images taken with it are not "super" crisp. Is this because I am not using auto focus correctly? Or does it yeild some slight fuzz atthe upper zooms out to 55mm?

And what would someone recommend as a good second lens? I am looking towards a zoom. Specifically the Sigma APO 70-300. I know again this is a top of the line, but my budget is limited for now.  Anyone have any exp. with this one? I see it retails for about 300, can get one for 1/3 that on ebay.

Thanks for any help/comments.
-B