Super easy and well written.

I was looking for WordPress and brain tree integration and stumbled upon this plugin that works in conjunctions with Gravity forms. I had not used Gravity forms before but after looking what what it can do, immediatly installed it and this pluign. Within minutes I was able to put my form together, configure brain tree sandbox feed and start testing. I would have given it 5/5 stars, but it’s missing support for recurring payments. According to the author who was super responsive, this feature is in work and next release will include it.