As a refactor over Vim, Neovim has greatly improved its code base. For example, some functionality is handled by libuv, the same code base that powers Node.js.

nvim supports plugins written in lua (and many other languages!). VimL is an awkward language to write plugins in, switching it out for other languages was a great call. Despite the fact that Vim can also have python-based plugins, NeoVim can do much more and much better.

NeoVim was a complete rewrite of Vim, with new features added and underlying issues resolved thanks to the Vim code base. The keybindings and configuration are the same as Vim, so the switch can be pretty simple.

The core text editor is "headless", meaning it's detached from the user-interface so other programs can hook into it. This enables better integration with IDEs and browsers, where "Vim mode" has typically been a poor substitute because it was a partial rewrite or a partial port at best. One of the advantages of Vim has always been ubiquity and Neovim makes it even more ubiquitous.

This avoids the user having to make any installations.

The core functionality is handled apart from the UI, meaning that Neovim can be embedded into any other GUI system, such as Atom.

Vim plugins have always been useful, but tied to specific languages. Neovim's architecture provides better separation between plugins and the core product, so that plugins are completely flexible and can be written in any language.

Not many editors can open such a large text file so quickly.

Some typical configurations most of VIM users make are default in Neovim.