Rust seems very much like modern C++. Borrowing, references and the like have nearly direct analogs to C++ references, unique_ptr and other STL constructs. Except the compiler enforces them with (my opinion) relatively more clear error messages most of the time and in some cases the syntax is actually clearer (others not necessarily).

My biggest struggle so far is overcoming the differences in the implementation of generics. I have yet to "fight the borrow checker," but the generics implementation is something of a hurtle for me.