Until vim 8, it was a drop-in replacement, retaining full compatibility with vimrc and all plugins. My switch was seamless, and that was a big goal of theirs. Vim 8 introduced features already found in neovim in an incompatible way, and now the real fork begins.
Well it isn't a drop-in replacement now. And it wasn't a drop-in replacement before either, on the platforms they needlessly removed compatibility with.
Vim introduced features that had been being worked on since before NeoVim, in a way that actually made sense in the context of Vim, and which fit into Vim nicely.
