If you're hardcore about evaluating digital cameras check out the ISO 12233 Standard Test Image, produced by I3A TC42 WG18. A finely detailed monochrome test image with features as small as .1mm. Take a snapshot of the $150 ISO image, measure your spatial frequency response, and you know how good your camera is.
I learned about ISO 12233 on Imaging Resource, as part of their fanatically detailed page about camera testing. The review of the S400 has the 2272x1704 WG18 ISO 12233 image if you need. Also, the viewfinder test confirms I'm not crazy - the optical viewfinder really is way off center.