I would not rely on this for non-trivial code. It also auto-suggests comments, which are sometimes right and sometimes a guess. For auto-filling boilerplate code, it has legs. And it's a nice delight when it predicts what I wanted. For proper optimized algorithms, no, not now

Is it significantly better than all the rust-analyzer helpers?

It's more substantial, yes. It offers whole functions if you give it enough context. It's a little shy with Rust, and more forthcoming with things like JavaScript. IME, VCS + Copilot does more than suggest individual structs, enums, etc: It suggests whole lines/blocks of code

Better is quite subjective. Copilot predicts what you want from what you've written, and offers a substantial amount of code at times. It's not always valid Non-AI tooling like rust-analyzer (which I've used) is better for listing your available valid options given the context

Eg, rust-analyzer will offer me objects and methods that are actually available and exist. Copilot guesses enum names, and just now got it wrong. I had to go to the documentation to find out the enum I really wanted It's like a static analyzer versus fuzzy logic, ish