Var is nice. But I generally prefer to not require people to jump out of the current code to figure out the type of a variable. And yeah, I've worked in those other languages, and navigating unfamiliar code with var everywhere can be confusing, so I try to avoid that kinda thing.

Records are nearly useless to me. Immutability is great, but I need a way to derive new sets of information based upon an set of information. And the only way to do that is bug prone.

Text blocks are nice for writing SQL queries and other multi-line things. But I'm not sure how often I actually use it.

Switch expressions are nice because it gets me compile time checking for things I would previously use a runtime check for. Other than that, as they currently exist, they're meh.

Sealed classes are something I've not had a use for. Maybe libraries will eventually make good use of them.

So I would say there's some nice QOL things in here. But I think "incredibly useful" is overselling it.

The thing is, lots of these things are built to support a longer term roadmap towards better support for data oriented programming. I think that is a worthwhile goal to drive for - and the sum of the parts (many of which are still in preview) will be less than the whole together - but we don't have the whole, yet. That, to me, would pass the "incredibly useful" bar.