@wiktor From a contributors point of view, it works really well. Once Git is configured for the project, formatting and sending patches is very simple.
I did have to set up mutt so I could send email in the required format - text-only and wrapped to 74 chars.
I have still not tired out the other side, reviewing and merging patches.
The server side needs work, I know a lot is planned, like better integration of lists with git and builds. A good interface could relieve some pain points.