CLI all the way! Though I have seen some really nice GUIs for it (Tower and Source Tree come to mind). Don't let using a GUI for Git get you down. I know quite a few great devs that only use a GUI for Git.

I also use Hub which is a CLI for GitHub and git-extras for some convenience commands.

The only thing I hate about CLI Git is the difftool (I believe it defaults to vi) so I switched to Kaleidoscope.

Definitely worth it for small projects, especially if you're prototyping new features or aren't sure if you're going to break the build. Starting a new branch costs almost nothing in terms of system resources and saves a lot of headache in the long run.

It can be for everyone. You just need to take the time to learn how it works and how to use it correctly (especially if you're working in a collaborative team).

I highly recommend reading Pro Git. v2 of the book just came out.