A big problem with Rust right now is that the documentation is awful. This has two implications. The less important one is that the language is harder to learn. The more important one is that there's no architectural document that prevents Rust from becoming a collection of features in search of an architecture. If you have to clearly explain in writing how something works, and the explanation is overly complex, that's an indication that simplifying the design may be necessary.

The basic concept of ownership in Rust is simple. Everything has either a single owner, or a reference counted cell as owner. Things which cross thread boundaries have a locked reference counted cell as owner. Temporary references to single-owner objects are allowed, but must have a shorter lifetime than the primary ownership, and this must be demonstrated by simple static analysis. That's straightforward.

Making those restrictions usable seems to require many features and much churn within the language. It's too soon to tell how this will come out. As I'm mentioned before, I'm bothered by the need for "unsafe" code in pure Rust that's not calling hardware or C code.