This is good, but the string handling stuff should be earlier in the tour, because Rust's strings are idiosyncratic (whole blog posts have been written about str vs. String, an issue that doesn't appear in most other languages). It'd be a nit, but handling strings is one of the most important things you usually need to know to be productive.
I'd love a version of this for people who know Rust that was just Rust idioms, similarly explained. I hang out in Slack channel with a bunch of Rust programmers (because I'm bumbling my way around in Rust as well) and it feels like there's a lot of communally understood idioms that aren't super apparent from the Rust Book.