Rust being a terse language with generics and macros, sometimes figuring out what type an object is is hard and can easily get lost. Rust analyzer + vscode instantly gives context visually in all my code and even names types better than when the compiler errors at you when you get it wrong. This is especially true when dealing with a lot of async rust and you need to know the exact fully declared type of an object so you can fully decl it's type for a pin/box to pass around. Game changer. Being able to use to jump to definition is a huge win. I can walk code so much easier now and understand issues without a lot of mental energy or digging. It also updates in realtime as I code.
Big productivity boost I know for a lot of devs on Fuchsia. It would take me at least twice as long to get up with a new crate and be productive with it. The same is true as my own code base grows and I can't keep it all in my memory and remember. Impossible to stay as productive as code grows in rust without something like this anymore.
Also a huge win for the fact that it works remotely with vscode's remote features so I can have my code + rust-analyzer on my big linux machine remotely but still edit that code and get the context locally on my dinky/slower/older macbook.
My only wish is that it eventually gains some of the deeper refactoring features in vscode you can still get in Rust + Clion/JetBrains. Almost there.