The EOS 7D certainly is a milestone among the recent Canon SLRs, new features most people were waiting for among them a new and finally real improved AF. But low noise is not something the camera is famous for. Well imho opinion it handles noise quite well 400 too 800 ISO is really no problem for the 7D even this pictures which was 1.7 stop underexposed and was therefor pushed in Lightroom 1.7stops looks good in my eyes. The noise clens very well with one of the available plugins like NOISENINJA or NEATIMAGE. The 18Mp are a challenge for every lens or lens/converter combination but even more for the photographer every little shake results in a waste of the high resolution and I am quite sure that the complains about soft pictures which show up in most of the forums are a result of the photographers sloppy technique.
In terms of noise I am quite happy with the results of shots 400ISO and more but I expected less noise in the range of ISO100-ISO400 but to be honest it is still on a level sufficent for even the largest prints and as long as my clients and the editors don”t complain I am happy as well.