- function and variable types are harder to visually parse for me. The keyword to declare a variable and the type put the varible name in the middle for instance.

- the "fn" keyword is terrible, just to save on characters. Honestly, any keyword should have vowels and is pronounceable. Python has "def", I would have been fine with "func" as well

- type annotation for templatization make is hard to read where the real arguments begin (for me). I puts info on the type in another place than the variable itself.

- "Mutable" feels like it should be all lowercase, to stand out.

In general, I know there are areas to improve on C++ syntax, especially on modules, but some choices seem different just for the sake of difference.