Wow! A discussion on Clarity rendering and not one contributor posts a before and after sample to back up all their words?
Apparently you didn't follow any of the links that were provided (here
are some more). There are also videos/tutorials/webinars on the TopazLabs website, where you can see the tool in action, or subscribe for webinars where a free copy may be raffled.
Besides, a tool as powerful as Topaz Clarity can be made to change the local contrast in so many ways that it makes it a very personal preference of how any image will or can be changed (for the better or for the worse, depending on how one defines that).
Also, because it reacts on local contrast, the effect will differ by image. Therefore, one of the great features (besides the great masking functionality and halo free adjustments) is that the image preview updates almost instantly as one changes the settings, making it a very creative process, where one looks at the image as one develops it without looking at the controls.
To humor you, I'll repeat an example (one of a gazillion possible renderings) I posted a year and a half ago, a few days after Clarity was initially released. It's actually more revealing to see it in action (instead of a before/after shot), which requires video:
Original rendering Original rendering + Topaz Clarity
One can make the skies more dramatic, less dramatic, change the saturation of the green in the waves, etc., etc., it is just one possible combination of settings. A tool like the Lightroom/ACR version of Clarity is simple, use more or less mid-tone contrast, but the level of control pales in comparison to how things are implemented in Topaz Labs' version. That also means that it comes with a learning curve, unless one is satisfied with the presets that come with the plugin.