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The sales representatives in camera stores tell me that the Superior Auto feature, on all Sony camera models that have it, will take away the shadows on the face from a hat on a sunny day in bright sunlight and smile line shadows on face shots. Is it true, or just sales talk, to get me to select a camera they recommend?
Not completely. The shadow areas remain, but they contain reasonable detail. Under normal circumstances during a high-contrast exposure (e.g. as you suggest, a sunlit scene with a shadow across someone's face from the peak of a hat), the camera's (or human's) exposure choice can be either a compromise between the light and dark, or it can favor one or the the other. What the Sony in-camera processing does rather well is to recognize the highlight and shadow areas and 'seamlessly stitch together' two (or more) back-to back shots with exposures respectively suited to the highlight and shadow regions of the frame. The result is a 'composite' photo that shows well-exposed detail in both the highlight and the shadow areas. It does this VERY well. Of course this 'flattens' the overall contrast somewhat, but the result of the in-camera processing is actually better than the result of any post-processing software (e.g. PhotoShop) that I have used. Post processing software tends to flatten the image more noticeably AND introduce some noise, whereas the Sony in-camera processing techniques tend to eliminate noise. (And there's no need to be a photo-geek spending hours to achieve the balanced result.)

I have two Sony cameras with this feature (HX 100V and a new WX 150). I find it very useful in many circumstances. There are lots of other reasons to choose Sony cameras too - all brands produce wonderful photos in good light, but the pocket-camera clincher for me (again) was Sony's Exmor R sensor, which (together with some in-camera trickery again) produces staggeringly clear and noise-free images in very low light conditions.

Hope this helps.