The sigma 24-70 I have is the sharpest lens I own. It is a superb lens and for a mid range zoom, you cannot go past it. It is the only lens I question myself about having the need to sharpen all digital photos.
I disagree with dche5390 comment that Sigma's use of the word macro is a lie and the suggestion it was a determined decision to mislead is extremely harsh, and I would think Sigma's legal department might be questioning statements like made above. You can get quite good macro shots with this lens, and their other zoom lenses that they stick the word macro on. However, it will not compete with a dedicated prime (non zoom) macro lens.
This was taken with my 24-70 on a Nikon D3