It's the oh-my-zsh of vim/emacs.
After a year of SpaceVim, when I finally found time, I ended up switching back to my more lightweight and stripped down version of NeoVim but copied the keymapping approach and some of the individual configs. It was a great starting point.
If you're a) new to vim/emacs or b) tired of maintaining your own config for w/e reason, Space[x] is entirely usable in it's default state with good documentation. It also updates often and stays on the cutting edge of various plugins and progression in the community, but with the stability of a larger community.
It defeats a lot of the learning/config curve arguments again vim/emacs.