I think it depends a lot on your workflow. If you're comfortable with, and used to, the command line this might not be for you. But for easy staging and committing of individual files/hunks I find it very useful. Also, even if you're just using Sublime Text as your commit message editor, this will give you color highlighting of you commit message, including gently nudging you towards good practices for commit messages.
You probably don't realize how much this slows you down.
I use git on the command line too, it fits well with my workflow (branch features, "commit -a" when it seems relevant, rebase/squash when ready).
Maybe a more complicated workflow could justify an IDE plugin, but for me CLI is fine.
Also, there is completion for git in shells such as bash and zsh.