This is partly a matter of taste, and since I don't find it distracting at all, there's no downside for me. But as far as value added, I find it super convenient. I like that gitgutter gives a quick indication of what chunks I've been working on and lets me quickly navigate between them (without having to remember to mark them/hit ^O) by hitting ]c or [c (I think these are defaults, but I might have overridden them). I also like that it lets you effortlessly interactively stage changes (in case you have a good hunk you want to commit before trying something more experimental out) as well as previews that show you diffs of specific hunks as well as the ability to selectively undo hunks. It also is a great way to immediately verify that a file is unchanged without hitting ^Z and running `git diff FILE` for the file I was editing. It's also an easy confirmation that I didn't accidentally change or break something accidentally. Obviously I run a `git diff` and tests before a commit, but for me, nothing beats seeing my diffs in the full context of the file to confirm that, yes, those were all things I did on purpose.

Ones that take up space are kind of annoying, I agree. I like IntelliJ's solution: mark with green, or yellow for additions and changes. It's a 1px line next to the line number, and also it's in the "minimap" type of view so you can jump right to where your changes are in a large file.