It works, but there are better alternatives – iOctocat - Mobile client for GitHub Review
I used the free version of iOctocat. Did it work as advertised? Splendidly. The free version, as advertised, does not allow commenting, posting, merging, etc. It's basically "read only" for GitHub data.
If you're as crazy about free software as I am, I recently switched to codeHub. It's open source, and the free version has tons of features (the pay version adds private repos in the mix, I believe).
If you prefer this UI or really don't need to ever comment/merge things, maybe (probably not, but maybe) iOctocat is right for you. Otherwise, try out the other app.
Review by OpenSourceIsBetter on
iOctocat - Mobile client for GitHub