When comparing Neovim vs GVim, the Slant community recommends Neovim for most people. In the question“What are the best open source programming text editors?” Neovim is ranked 2nd while GVim is ranked 16th. The most important reason people chose Neovim is:
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.
Specs
Question Ranking
Pros
Pro Still Vim but with upgraded features and some issues fixed
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.
Pro Better integration with external tools
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.
Pro Modern code base
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.
Pro Powerful plugin model
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.
Pro Built-in terminal emulator
This avoids the user having to make any installations.
Pro UI Agnostic
The core functionality is handled apart from the UI, meaning that Neovim can be embedded into any other GUI system, such as Atom.
Pro Async plugin execution
Pro Active development community
Pro Comes with some good configurations out of the box
Some typical configurations most of VIM users make are default in Neovim.
Pro Opens a 3Gig Text File in a few seconds
Not many editors can open such a large text file so quickly.
Pro Fast and light on memory usage
New neovim editor instance starts instantly and you can have multiple editors open at the same time, because id does not require a lot of memory to run.
Pro Work in TUI (Tex User Interface)
Neovim can work on terminal, on a remote server over ssh.
Pro Terminal mode is very convenient for testing code in a split window
Pro Vim without a shell
When opening files from the file manager, it is still nice to have vim.
Pro Excellent performance
Because it loads the whole file into RAM, replacing all string occurences in 100MB+ files is quick and easy. Every other editor sort of died during that.
Pro Works on all platforms
Whether its your windows machine, a Linux, Unix or a Mac Vim would work everywhere. You can even build it from its source on your favorite linux environment.
Pro Has different cursor shape in command and insert modes
Unlike vim, gvim has different cursor shape in command and insert mode, which is very convenient.
Pro Supports all vim features and settings
All vim features, custom settings, and plugins are automatically available.
Cons
Con No stable release yet
As of yet, Neovim is in an unstable point in it's development. There is no stable release and using it for the moment should be done with caution as many features may change in the future.
Con No graphical editor yet
At the time of writing this, no equivalents to gVim exist.
Con Limited cross platform support
Neovim is not available for many legacy platforms.
The Windows version is currently considered experimental.
Con Ambiguity in extensive documentation
Con GVim, like Vim, has a difficult learning curve
A lot of time is needed to learn all the commands and modes supported. A lot of time will also be spent tuning all the settings to the user's preference.