I haven't used SmartGit, so I can't really compare.

I would single out the following for Magit:

1. Single key strokes for actions and toggles 2. Discoverability through "slide-ins" (TFA also explains this)

For 2, this means I press "c" for commit, this opens a popup showing me the next keypresses and what they do. So I can build up muscle memory for commands I know that are fast due to 1, and I can discover options that might help me due to 2.

If I don't know what to do at all, there's Ctrl+c, Ctrl+c to discover "entry-points" for Magit shortcuts.

I would also highlight that in Emacs magit one can always drop back to command line by pressing "!", which I do, when I don't know how to do something in Magit. Like "git submodule update --init --recursive".