I like that it pulls the theme from my website in regards to fonts, colors, and sizes. Makes it easy to fast create custom calculators without spending time on ensuring design consistency. It's also really easy to create custom calculators using your own formulas. Most of the other plugins that I found only have a few templates with "most common calculators" options.

I like the function of the application itself, it is very useful to set up clickable charts for our site.