I had this lens for awhile and it did perform very good but in order to get good sharp images I found that you had to be up around f8. I didn't sell because of this though. I had gotten the 300 f2.8 L IS and the 500 f4 L IS. I found that I just wasn't using the 400 focal length as much as I should and decided sell it before it became too big a paper weight.

For someone that is looking for a good 400 lens, I can certainly recommend this lens. It is light enough to be very much hand holdable.