I've been a very happy neovim user for over a year now (on linux). My switch was pre-vim 8 so the ability to have things (like plugins) run asynchronously was a huge plus, but now vim has that too.
For me the biggest selling point is the plugin architecture, I've been a vim user for over a decade now, and I'm only writing my own vim plugins now, because neovim allows me to do that in the language of my choice (ie. not VimL).
Compare this to VSCode, Atom or IntelliJ.
My (perhaps uncharitable) understanding, as a dedicated vim user with no thought of switching, is that vim has that because of Neovim. (On rereading, I guess this is what desireco42 (https://news.ycombinator.com/item?id=15650991) means by the "kick in a butt that Neovim provides for vim".)
Python example:
import vim
# Show current directory in Vim
cwd = vim.eval('getcwd()')
cmd.command(':Explore %s | redraw' % cwd)
It's not complete coverage, but it's not "the API is just a thin Python wrapper around Vim commands as strings" as your comments suggest.
I'm not trying to be mean or mislead. I've used vim for decades, and emacs too for that matter. My favorite editors by far.
Vim gives you buffer, window, cursor and range, plus eval and command. The eval/command stuff is a "shim", insofar as you have to wrap them yourself if you want more programmatic access; like you'd have to do `def getcwd(): vim.eval('getcwd()')` But for a lot of what you want to do, you're messing with buffer/window/cursor. I wouldn't call it a full-featured scripting API, and certainly Neovim's is better, but your posts suggested all the scripting API was was just an entry point to ex commands. There's a lot more than that, to the extent that it covers most of what you want to do.