Most would agree that Git's command line leaves a lot of room for improvement (although the manpages are quite good at explaining). But the internal concept is sound.

I find it a bit odd that no-one has come up with a decent GUI or an improved command line tool for Git yet. There's plenty of attempts to supplement Git with extra commands but that's hardly an improvement. There are several implementations of the Git plumbing parts (e.g. libgit2), so making an UI on top of it wouldn't be that much work.