I'm most excited for the treesitter integration and its potential to amplify Vim's "killer feature": text editing as a language.
Vim's editing language feels most powerful when I'm using its text objects: "ciw" means "change in word", "cis" means "change in sentence", and so on. But Vim's built-in text objects are not always a perfect match for the code you're editing. Suppose you want to change the first argument of a function, for example; there's no built-in "first-argument" text object. But Treesitter integration makes it easy to create text objects that understand the AST. Without much effort, users will be able to make mappings like `cia1` to "change in argument 1", and these mappings will work across all languages with Treesitter support.
Do you find your brain can actually work that way? My issue with all of these relative jump points, repeat this N times, etc of VIM is by the time I’ve calculated in my mind what the command should be I’d have already done it with just standard navigation/mark/yank/repeat. But perhaps you have galaxy brain ;)