I don't understand why people are so lyrical about; it's just NOT sharp on a dSLR.
Probably the sharpest zoom on a SLR, but if you only shoot digital: do not buy this.
The focus is right-on tho, but 9 out of 10 times I will end up with an unsharp image; and I'll have to do a lot of post-processing to come up with something useful. Tested it with two copies on two bodies.
Also take a look at userpictures @ Pbase.com if you think i'm wrong. Almost every image taken with a dSLR is relatively unsharp.
Don't be mistaken by his legendary status, save yourself a lot of trouble and get the 17-55/2.8; which gives much better results.