The value of IntelliJ (in my opinion) is the deep semantic processing of the language you are using to provide useful information/refactoring/linting capabilities. It blows the equivalent LSP stuff out of the water (or at least it did last time I tried it with Kotlin).
As an editor, I really hate it coming from vim. Even with vim mode, it sits in the uncanny valley for me. It's pretty close to vim, I'd say 95% of the stuff works as I'd expect, but the last 5% is jarring. My biggest annoyances are:
* The undo behavior is insane, I'm constantly double-tapping u, because undo brings your cursor back to your last edit, but doesn't undo it. Unless your cursor is already where it should be, then it will undo. So it's uu then ctrl+r (sometimes).
* They don't have vim tabs (I don't think any modern IDE does). I'm constantly closing and reopening splits, it drives me crazy.
* There's no toggle fold, gotta explicitly unfold/fold. That muscle memory is stuck with me now, even in vim which makes me sad.
* Moving between the different panels is not the same as moving between different splits. You need to memorize the hotkey for each panel and then the hotkey to get back to the code, it feels extremely unnatural. The vim hotkeys are hit or miss in the different panels as well.
Despite all that, I still used it when I was working on a Kotlin codebase. I wish it was possible to extract their language processing stack and use it in vim to have the best of both worlds.