Some random things off the top of my head:
* No block cursor (the block cursor plugin doesn't really work)
* When you switch between files, it keeps jumping back to insert mode, but you don't immediately notice (especially since there is no block cursor). There's a setting, but I've never been able to make it work.
* Autocomplete and the dot command don't work together
* Macros are flakey
* Visual mode and the dot command don't work well together
Otherwise, here's the issue page: https://github.com/sublimehq/Vintage/issues?state=open
About 25% of those issues annoy me personally. There are a lot of commands that leave the cursor one off, which messes with my muscle memory.