i started using github somewhere in 2009 iirc. i was a bit reluctant to use it back at that time, especially because of its speed (or lack of, actually)... and because i already hosted my projects of repo.or.cz.
however, i'm now really glad i started using it. speed is no longer a problem, and it provides really nice features. cia integration, network graphs, comments on commits, watching repos (even if i'm not totally happy with it right now), and of course... pull requests!
i was away this week-end, and found 4 pull requests in my mailbox for my modules when i came back. integrating other's work has never been easier with git and github which allows people to fork at will. that's the new way of writing code: create the basic stub of your module, and wait for others to enhance it! :-) git plugin for dist-zilla now supports pushing to a different branch, supports the new dist-zilla-tester framework and the bundle @git now accepts multi-valued args.
dvcs are a bit harder to grasp at first, but once you understand the concepts, they're really a killer application - especially when coupled with a cooperative platform such as github.