Nearly everything we do is out in the open, and most features are available in CE, which is fully open source (https://gitlab.com/gitlab-org/gitlab-ce). I've wanted great, open source tools that don't look like dung for a long long time, and GitLab is definitely reaching that goal. Can't help but gush about the product we're building. :D
Here are some of my favorite upcoming features: https://gitlab.com/gitlab-org/gitlab-ce/issues/17575, https://gitlab.com/gitlab-org/gitlab-ce/issues/14661, https://gitlab.com/gitlab-org/gitlab-ce/issues/15337