I find github compelling enough to pay them for private repos. $84 a year gets me five private repos. If you want to win me (and others like me) over you'll have to sell me an improved experience.
hzy has it right on the money. It's rock solid and reliable. The built in issues/pull requests/wiki are fantastic. Adding in a collaborator is easy. It's credentials I already heavily use.
One of the most compelling feature of using GitHub for private repositories is developers already know how to use it, already have accounts etc. GitHub has a nice growing moat in that regard.
I find issues and the wiki to be the
weak points of github.
What's wrong with GitHub's wikis?
I recently evaluated wiki software that I could use with one of the teams I'm on, and I was surprised when I ended up choosing GitHub's wikis. I love that their wikis support Org Mode's syntax. The only other solution I could find that supports Git and Org Mode's syntax is Gitit, which was my second choice.
I was fully prepared to use Markdown, Textile, or some other lightweight markup language that I consider inferior to Org Mode's syntax, but no wiki solution was good enough to warrant that compromise.
