Most of professional stills photographers don’t even know this but here’s the thing.
With mk2 and all the other Canon cameras with Picture Style, there’re mainly two types of Pictures Styles. Standard and Neutral. All the other built-in Picture Styles are based on the Standard one.
Regardless of NR setting, Standard PS smears detail even at ISO 100 in order to reduce noise. For a simple test, take a picture using those two PS and compare the difference. The difference is quite huge.
It gets even worse when you apply default standard NR setting since it does double smearing. This has been the key reason why Canon cameras do poorly in photography review since default setting of the camera uses Standard PS with standard NR.
Quoted from Philip Blooms website. It was a response to his review of the 5d3(in which he also said it was a bit soft).