Here you can see the Smart Sharpen Filter compared to the original image and the same image sharpened with the USM filter. Although this example is small and has been compressed for the Web, you can see the difference, especially in the fine hairs of the bee, the highlights, and the flower details. The improvement is more apparent in full resolution images. I have provided two larger images that you can download to compare the results for yourself. Open the examples in Photoshop, and turn the layers on and off to compare the original photo with the unsharp mask version and the smart sharpen version.
PSCS2-smartsharpenbee.psd (1.23 MB)
PSCS2-smartsharpenbark.psd (1.14 MB)
Zip file containing both files (2MB)