I love Go, but lack of generics just kills me every time I have to write a manual non-semantic for loop instead of using an enumerable like select in Ruby.
Also, pointers are horrific and need to be replaced with pass by reference with an immutable “borrowing” option.
Some other nits are needing superfluous return statements, not having full closures. Too hard to DRY up my code.
Biggest wins are composition instead of inheritance, and lack of optional args. These are the biggest anti-features in modern languages.