Hope I don't get burned for saying it, but lack of real IDE support in rust is pretty annoying. With tools like racer you can still be productive, but things like rename refactoring or searching for uses of functions are things I miss most from languages like Java or go, which have good support.

There's been some talk for a long time of a rust oracle for code indexing (to support ide use), but there hasn't been much progress (or interest?).