Compared to Go or Java you're not missing much - I'm not sure what the state of Rust's generics is these days but at the very least they're not far behind Java's. Compared to a higher-level functional language you're missing higher-kinded types that would let you do things like http://typelevel.org/blog/2013/10/18/treelog.html . See what you end up doing for "cross-cutting concerns" - things like logging, auth, transactions - as those are the kind of thing you need a higher-level language to handle elegantly.

The big thing you're missing compared to the mid-level languages you mention is garbage collection. Rust makes manual memory management much easier than C++, but it's still never going to be quite as easy as the "just make objects and don't worry about it" that you get in a garbage-collected language.