I used to have the first version of this lens (the primary difference is a built-in hood) and liked it. I used it for studio portrait work (here's a sample shot), and for that it was very good. I never used this lens outside of the studio. If you intend to make full body shots with good background separation using this lens your studio will have to be fairly long. I sold this lens after a year or so because I didn't use it as much as I could have - I have a 70-200mm that is much more versatile.

This lens does not have the reach necessary for shooting wildlife - for that you will need at least a 400mm lens.

@Chode, I think with this lens you do not have to fear it is not sharp enough..

tnx!