These images are screen shots of the RAW image opened in Aperture 2, with the loupe set at 200% over a similar part of the lighthouse. I have to admit I was disappointed with the results - I was expecting to see a "slap in the face" major difference from the new lens.
Image 1: 70-200mm 2.8L USM non-IS

Image 2: 55-200mm 4.5-5.6 USM II

I know that the screenshots probably don't present the images well enough to analyse properly but obviously the RAW files are too large to post. I also know that PP can help significantly with RAW images but I still thought that I would see a more dramatic improvement in sharpness with the new 'L' lens.
Can anyone comment on my expectations or perhaps offer a better way of comparing the lens performance?
Thoughts are much appreciated.
Thanks, Muzz

do this comparison again in an environment where you have more control over the conditions. Gary is very right to point out the differences in contrast in the lower left corner!