Looks interesting. I develop on Windows, Mac and Linux platforms. My desktop is Windows+Mac, and I'm currently using TortoiseGit on Windows and GitX on Mac, plus the command-line where necessary or more convenient. I haven't done too much Mac development in the last few months, so this is from memory - the situation may have changed since.

I would guess GitX is your main competition. GitX is perfectly friendly, and quite useful for staging and making commits on a single development branch, but doesn't exactly have great coverage of the other features of git that I use, so I end up resorting to command-line relatively often. Good for me I'm sure, but it hampers my workflow a little, especially if I have to start diving through docs when I know what I want to do, but need to look up the arguments to do it.

With that said, I'd welcome a more complete Mac Git GUI, and I look forward to tracking your progress, and evaluating your product when possible. Best of luck.