Yes, I had an issue with mine. All of my shots at f/1.4 were a little blurry. I shoot with a 60D, and so I do not have microadjustment, which I am under the impression would have fixed the problem. While I was in New York, I went to B&H (the vendor I bought it from), tested a copy that they had behind the counter, and the shots taken with the tester lens were much sharper. I instantly swapped out my copy for a different copy (B&H's customer service is amazing). The new copy worked much better from the get-go. Needless to say, my next body will have microadjustment. You should not have this problem, as the 7D has microadjustment.
I think the issue is that the lens is manufactured in conformance with its specs, but that it may be more susceptible than other lenses to require microadjustment. Any others want to chime in on this? I am merely speculating here.
