Experience with Grapevine?

I recently had a coworker who was invited to join a Grapevine circle. He wasn't familiar with it so he asked me if I was and if I would check it out for him. I hadn't heard of Grapevine previously, so I gave it a look. I wasn't able to find a lot of the information I was interested in, such as what charities the group supports, how effective they are with their donations, how effective the charities are, etc. This lack of transparent info is a red flag for me. But, I'm curious if anyone out there has experience good or bad with Grapevine who would be willing to share?