I don't like to be that single critic but hey - it has to be said. Gravity Forms is great plugin but documentation is way far from being good. Recently I switched to GF from Ninja Forms and studied all GF docs. Then I had to open the code and see how it actually works. Then I've built a complete user frontend, membership and payment solution for community website, without using any extra plugins like GF + Custom Post Types etc. It's kinda strange for me - most plugins that rock (ACF Pro, GF etc) suck in docs.