I've noticed it get drastically better. I never used to be able to use it at all. It was just a pointless exercise. Now it works for everything I use it for, which isn't a lot, but I don't get any issues.

I haven't noticed anything because the only thing it ever managed to do reliably is set timers so that's all I ever used it for.

and one in 20 times you'll get a "here is the timer" where it just shows you yesterdays already complete dinner timer

Siri is now a term used by Apple to cover many virtual assistant applications, not just the conversational side of things. The article goes in depth about things such as Siri Suggestions and pro-active notifications based on patterns and context.