Wow. I wrote that article on LtU last night, after going over there to see what the language theorists were saying about Rust. (And after, for the third time in three weeks, having my Rust code fail to compile because the Rust crowd changed the language again, after the "alpha release" and its claims of stability: http://blog.rust-lang.org/2014/12/12/1.0-Timeline.html) I wasn't expecting it to be picked up on Hacker News.

Rust is going to be very important. The ownership system is a major step forward in language design. It's a huge improvement over C/C++.

It's not easier to write than C++. Rust may feel clunky for people coming from Javascript, Python, Ruby, and PHP. Having to think about lifetime issues for mere strings is a new cognitive load. The big win with Rust is that most of the errors are caught at compile time. This is Rust's big advantage, but alien to scripting programmers. The Rust compiler report errors in three phases. First you get all the syntax errors, and until the syntax is perfect, that's all you get. Then you get all the type errors, and until the type issues are perfect, that's all you get. Then you get the ownership errors. Ownership is a global analysis; ownership problems involve at least two points in the program. The compiler produces good, but very wordy error messages. (Hint to Rust developers: put in a line length limit and word wrap for long compile time error messages.) If your ownership design is faulty, the result is likely to be "fighting with the borrow checker", because the problem isn't local, and just fixing the compiler-reported error will make the problem pop up elsewhere. The cleverness of the ownership system is impressive, but some programmers are going to feel like they're being hammered by it. Successful C++ programmers won't have a major problem with this. It may be tough on the Javascript crowd.

Rust requires some advance planning, which may be incompatible with "agile" development. It's also difficult to port code from other languages to Rust without rethinking the ownership and bounds logic. There is a port of Doom to Rust. It has a lot of unsafe code, because Doom's internal memory structures are not directly compatible with Rust's. Such problems will recur as big packages with delicate internals are ported over to Rust.

This is partly a documentation problem. The current tutorial (http://doc.rust-lang.org/book/hello-cargo.html) is relentlessly upbeat and glosses over too many of the hard problems. Once some third-party books have been written, that situation should improve.