if you are already using a GUI for your IDE, is it really faster typing on the command line than right clicking on your git root folder in explorer -- that in my case is usually on a different monitor -- and clicking on git commit where you can see all of your changes, and then double clicking on a file to bring up your diffs?
Don't get me wrong, knowing the command line is invaluable when it comes to corner cases that just don't work well in a GUI and automating tasks.
Yep, it's absolutely faster - a command line is simply more responsive than moving a mouse and clicking dialogs if you know exactly what you need to do. I've always used an IDE but I exclusively use the command line for VCS. Setting up a commit is much easier to do if you know all the commands over the tedious drag/right click/choose dialog.
As to your use case, git diff has never failed me.
This is all aside from the fact that the CLI is ubiquitous. One day you'll be in a situation where it's all you have access to, and you'll thank yourself for having learned it (or kick yourself for not).
When would I only have access to the command line as Windows developer? The most I would have to do from a command line in my usual day to day work is use git pull to automate my deployments. But in that case, I also need to know the ins and outs of msbuild. That doesn't mean I'm going to use a regular old text editor and build with msbuild in my daily workflow.
Don't get me wrong, knowing the command line is invaluable when it comes to corner cases that just don't work well in a GUI and automating tasks.