- The borrow checker is one of the easier parts of Rust to grok, it's just as you say, not that complicated in the end.
- Traits are more annoying to understand and find in source code when they can get added from anywhere, and suddenly you code gets extra functionality, or it's missing the right one unless you import the right crate but there is no "back-reference" so you're not clear what crate the code actually comes from.
- Crates/libraries are harder to grok with their mod.rs/lib.rs files and whatnot, in order to structure your application over many files.
- Macros are truly horrible in Rust, both to write and debug, but then my only experience with macros are with Clojure, where writing macros is basically just writing normal code and works basically the same way
- Compilation times when you start using it for larger projects tend to be kind of awful. Some crates makes this even worse (like tauri, bevy) and you need to be careful on what you add as some can have a dramatic impact on compilation speed
- The async ecosystem is not as mature as it seems on first look. I'm really looking forward to it all stabilizing in the future. Some libraries support only sync code, others only async but only via tokio, others using other async libraries. Read somewhere that eventually it'll be possible to interop between them, time will tell.
- Control flow with Option/Result and everything that comes with it is surprisingly nice and something I'm replicating when using other languages (mainly a Clojure developer by day) now.
My development journey was PHP -> JavaScript -> Ruby -> Golang -> Clojure with doing them all the capacity of backend/frontend/infrastructure/everything in-between, freelancing/consulting/working full-time at long term companies, so take my perspective with that in mind. Rust would be my first "low-level" language that I've used in larger capacity.
I have been using Rust professionally as well and had a different experience. For anything singlethreaded I agree with you. For any asynchronous behavior, whether it's threads or async or callbacks, the borrow checker gets very stubborn. As a response, people just Arc-Mutex everything, at which point you might as well have used a GC language and saved yourself the headache.
However, enums with pattern matching and the trait system is still unbeatable and I miss it in other languages.
I know dealing with the borrow checker can feel like a dead-end sometimes, but dealing with it is something that you can learn. Things that it can't handle fall into a handful of common patterns (like self-referential structs). Once you learn what not to do, you can recognize and avoid the issues even before you write the code.
Obviously i'm biased, but i quite enjoy it. I find i am more efficient now than before, because it manages to give me the ease of the "easier" languages quite often with a rich set of tooling when i need to go deeper.
Personally i feel the concern over the borrow checker is way overblown. 95% of the time the borrow checker is very simple. The common worst case i experience is "oh, i'm borrowing all of `foo` when i really want `foo.bar` - which is quite easily solved by borrowing just the `.bar` in a higher scope.
The lifetime jazz is rarely even worth using when compared to "easier" languages. Throw a reference count around the data and you get similar behavior to that of them and you never had to worry about a single lifetime. Same goes for clones/etc.
I often advocate this. For beginners to use the language like it was a GC'd language. A clone or reference count is often not a big deal and can significantly simplify your life. Then, when you're deeper into the language you can test the waters of lifetimes.
So yea. Your mileage will vary i'm sure. But i find Rust to be closer to GC'd languages than actual manual languages, in UX at least. You won't screw up and leak or introduce undefined behavior, which is quite a big UX concern imo.