The form builder is very intuitive, easy to use, and very flexible.
The plugin works as described with no bugs I can detect (rare in free plugins).
The flexibility of what you can do with the submitted data is great. The per-form handling options make this super-powerful.
I've been doing WordPress sites for about 10 years. This plugin blows me away and will be a part of every site I create from here out. I adopted this for use on a college website.