I believe usability is the most important trait for a software product, and not only does Git have terrible usability, but its designed in such a way to make it nearly impossible for anybody else to improve its usability. (Although they can improve it's accessibility somewhat-- not everybody is capable of using a CLI interface.)
And it's in a product space (revision control) where the average product's usability is already bottom-of-the-barrel. It's kind of impressive in a way they managed to deepen the barrel a bit.
I'm forced to use (struggle with) Git at work, over my objections. There's no way in hell I'd use it for a hobby project where I have a choice.
I see just sharing my opinion of Git is enough to get voted-down on this site. Oh well. Vote me down. "Person dislikes something popular!" is obviously worthy of derision.
As for GitHub, I've downloaded libraries from it, but I have a pretty healthy dislike of Git, which is awful, and refuse to use it for any personal projects. (I only use it at work because I have to-- in any case, work repos are of course private.) I used to have a few projects publicly available on Google Code, but now that's shut down, so there's really just nothing. I do have private repos for my hobby work.
In case it matters, most of my development is in C#.NET.