I disagree; `hg` is a CLI as well, but it's far simpler and safer than `git`. That said, I have far more experience with git than hg. Further, gitless itself is a cli, and it's also simpler than git.
If simplicity was the goal of command line interfaces they wouldn't exist. This is not ls or cat, nor is it trying to be. hg might have a better CLI than git, but it still doesn't justify something like gitless.
You need a really compelling reason to layer another level of abstraction on top of git and from what I can tell, having branches be full sets of working files isn't really a good enough reason to make that switch.
Where are the improvements in Gitless exactly? Pretty telling they don't even list them in anywhere.