There are lots of substantial improvements coming! I'll point to some points that appeal to me personally that aren't big enough to make headline news given how much else is coming.

Neovim also adds:

vim.treesitter.select()

for starting or adjusting visual selections based on syntax-tree nodes.

AST-aware editor interactions are something I've really been missing since leap-ast.nvim was archived. Maybe there's a good plugin for quick selections or text objects based on AST structure that I haven't gotten around to trying. But I'm looking forward to built-in building blocks!

Edit: Wow I'm dense - leap-ast was archived because Treesitter integration is now built into leap.nvim.

Neovim now exposes a logging interface:

vim.log

Sounds like a quality-of-life change that will be real nice to have when you want it! I hope this will replace my uses of print(vim.inspect(...))

There is now:

:bcd

for setting a buffer-local current directory.

I've been surprised in the past that this wasn't possible before.

And finally, the :restart command to apply your updated editor config while preserving your open buffers and windows!