Here's a great blog post about designing Github For Mac. http://warpspire.com/posts/designing-github-mac/ Basically they didn't want to build an app that maps git commands to buttons. That doesn't make things any easier for anyone.

I think the GitHub app is fantastic, but the stability was definitely an issue. I love that I can use it without having to really know how to use git. (I can use git from the command line just fine, but find the app much nicer when it works)