Topaz clean is cool because it has effects that are different than all the other photo editing software. It is meant to "clean" up a photo by removing details. THe only preset I like with it is the "Curly Smooth" preset, it removes the details form the photo but keeps the curves. It looks really cool on trees limbs and such, other than that the rest of the presets are interesting but I have never posted a photo that has used any other than "Curly Smooth"
YOu can see the "curlyness" in these photos I have posted that were processed with Topaz Clean.